For this evidence-based 2026 list of misdiagnosis lawyers serving Markham, we reviewed the work firms handle and their published results, with reviews and professional recognition also considered.
Our featured firm in Markham is Diamond & Diamond Lawyers LLP, where Jeremy Syrtash leads the medical malpractice group. Paul Cahill caught our attention during the review because medical negligence is his focus, with trial results available to read. Before you call, find out who handles delayed diagnosis claims and what you'd pay in fees and case costs. Ask when your limitation period ends under Ontario law, rather than trying to work out the deadline yourself.
Jeremy Syrtash leads the medical malpractice litigation practice at Diamond & Diamond Lawyers LLP. He earned a BA from Yeshiva University (2010) and a JD from the University of Ottawa (2013), was called to the Bar of Ontario in 2014, and has acted as counsel and co-counsel in medical malpractice cases across Canada, many involving pediatric and obstetrical negligence.
Called to the Bar of Ontario, 2014 · JD, University of Ottawa · Best Lawyers: Ones to Watch in Canada, Health Care Law (2024 to 2027)
Paul Cahill's published results include an $11.5 million jury verdict for a child born with cerebral palsy and a successful trial against an emergency room physician after a mother's death. These aren't misdiagnosis results, but they show courtroom work in medical negligence. Medical malpractice makes up a substantial share of his work, which includes claims about delayed diagnosis and hospital negligence.
Stood out in our review for the recognition it has earned and how much of its work is medical malpractice.
We order firms by how much of their work is medical malpractice, the results they publish, what their clients say, their experience, their standing with the regulator and the recognition they have earned, all from public records and the firms' own sites. How lists are made
Thomson Rogers LLP dates back to 1935, so the firm has been around a long time. According to its site, its medical malpractice success in Denman v. Radovanovic, 2024 ONCA 276 was upheld on appeal. The firm says it handles misdiagnosis claims, with birth injury and surgical errors also listed among its work.
Stood out in our review for its years of experience and what its clients say.
We order firms by how much of their work is medical malpractice, the results they publish, what their clients say, their experience, their standing with the regulator and the recognition they have earned, all from public records and the firms' own sites. How lists are made
Not sure who to call first?
Tell us what happened. A malpractice lawyer who serves Markham can look at it with you, and it costs nothing.
Best for: Neurological injury and diagnosis claims
If a missed diagnosis involves neurological injury, Neinstein LLP's listed practice gives families a concrete place to start. Its listed work includes stroke and cerebral abscess, along with spinal abscess. Alongside paediatric injury, the firm's site lists work involving misdiagnosis.
Stood out in our review for how much of its work is medical malpractice and the recognition it has earned.
We order firms by how much of their work is medical malpractice, the results they publish, what their clients say, their experience, their standing with the regulator and the recognition they have earned, all from public records and the firms' own sites. How lists are made
Best for: Families prioritising regular communication
One Bogoroch & Associates LLP reviewer says, “They always returned my calls and emails quickly,”. Reviewers often mention how staff communicate and support patients. Although one person reports missed follow-up, the firm's Google rating stands at 4.9 from 210 reviews.
Stood out in our review for the recognition it has earned and what its clients say.
We order firms by how much of their work is medical malpractice, the results they publish, what their clients say, their experience, their standing with the regulator and the recognition they have earned, all from public records and the firms' own sites. How lists are made
Explain what diagnosis was missed and when you first learned that the delay might have hurt you. To check your deadline, the lawyer reviews Ontario's 2-year discovery-based limitation period and considers the 15-year ultimate period, including whether your claim falls under the rules for minors.
Review the medical records
The lawyer reads your chart to see what information the provider had at the time. Ask what other records or medical opinions would help investigate the delay after you've talked through the test results or referral with the lawyer.
Start the claim
You can start an Ontario claim without an affidavit or certificate of merit, since neither is required at that point. Medical support is still necessary. Before the lawyer files your statement of claim, ask them to identify the deadline that applies to you.
Develop medical support
The court's rules require you to serve expert reports in practice, addressing the standard of care and causation in your claim. Those reports set out the care you should have received and address whether the provider caused or contributed to your injury by acting, or failing to act.
Discuss resolution or trial
Before considering a proposed resolution, have the lawyer explain it and what you'd be choosing between if you kept pursuing the claim. The published results listed here include trial verdicts and an appeal. Those results won't tell you how your own claim will end, or how long you'll be waiting.
Malpractice claims in Markham: the rules that matter
The filing deadline in Ontario
The clock startsWhen you found out, or should have
Time to start a claim2 yearsMiss it and the claim is usually lost.
At the very most15 yearsafter the treatment, with a few exceptions
Limits on damages in Ontario
Pain and sufferingCapped at about $484,330
All damages togetherNo overall cap
Expert paperworkNo affidavit or certificate of merit is required to start a claim.
A written agreementThe share the lawyer takes, set out before work starts.
If you recover moneyThe agreed share and the case costs come out of it.
If the claim failsNo legal fee on a contingency agreement. Ask about costs.
With contingency fees, which several listed firms offer, the lawyer receives part of any money recovered; you don't owe a lawyer's fee if your claim fails. That excludes case costs. You might still have to pay for medical records, with medical opinions and court fees adding separate charges. These listed fee terms don't say who pays those expenses upfront, or whether you'd owe them if the claim fails. Don't sign without checking first. Before agreeing, ask how much of a recovery the lawyer would keep after deductions, including what would come out for costs you must pay yourself. Even a free consultation doesn't make the case free.
According to seven of the eight listed firms, their consultations won't cost you anything. Contingency fees are a payment option at six.
What to bring to your first call
A short timeline you've written showing when symptoms and appointments occurred, including the diagnoses
Copies of medical records you already hold
Your test results and any referral letters
A list naming the providers involved
When you learned of the missed diagnosis and possible harm, recorded as dates
Your bills and details of work missed
Hospital or insurer letters you've received
If you have relevant photos, those as well
Questions to ask a lawyer
1When a diagnosis like this was missed or delayed, have you handled claims?
2When my records arrive, who reviews them and handles my file?
3To work out my limitation period, what information do you need, and what deadline applies?
4For my claim, what medical opinions are needed?
5If money is recovered, how will you calculate the fees?
6If my claim fails, who covers the case costs?
7When I need answers or updates, how will you provide them?
8If you decline my case, can you tell me why, including any concerns you have about deadlines?
Choose around the missed diagnosis
Start with what's worrying you about the diagnosis. Perhaps a test wasn't ordered, or nobody followed up on a result; you may instead have received a diagnosis only after your condition had worsened. Ask about claims involving similar allegations when you explain what's worrying you to the lawyer. A firm's general injury work won't tell you how it would review your chart, so ask how it would connect the delay to the harm you suffered.
Each family weighs office location differently. While Reyes Tam Law has a Markham office, several listed firms are in Toronto or North York, with Bergel Magence LLP's listed office in Oakville. Ask where you'd meet the lawyer. If you'd prefer another language, check whether the firm can support you throughout the file, not just when you first contact it.
Use the consultation to test the working relationship
Ask who reads your records before you proceed, including who decides whether to accept your claim.
Ask for examples of comparable diagnostic delay claims they've handled. Past results can't tell you what will happen.
Ask how you'd get file updates and who would answer your questions if you couldn't reach the lawyer.
Ask how the firm would investigate whether earlier treatment could have changed what happened, including which medical opinions you'd need for that work.
A free consultation lets you ask whether the firm would take your case, without paying just to have that first conversation with the lawyer. Talking about your case doesn't mean the firm has agreed to start proceedings; it must first accept you as a client. Ask what you need to do next if the lawyer wants to see records before making a decision. Ask whether you're still responsible for any deadline if the firm turns you down.
Don't sign the fee agreement until you've read it. If money is recovered under a contingency arrangement, the lawyer gets a share; a failed claim doesn't leave you owing a lawyer's fee. Case expenses are separate from lawyer's fees, so ask who pays them upfront and what you'd owe yourself. Be cautious about anyone promising a result, especially if they won't tell you how their fees would work. Don't calculate your child's deadline on your own, because the limitation rules for children's claims aren't the same as those for adults.
Questions people ask
How long do I have to start a misdiagnosis claim in Markham?
Ontario's basic limitation period gives you 2 years after you discover your claim. Discovery requires you to know, or reasonably be expected to know, that you've been injured and the provider contributed to it, as well as knowing that bringing a lawsuit was appropriate. A 15-year ultimate period also applies. The clock may start on a date other than diagnosis. Ask an Ontario lawyer which dates they need to work out your claim's deadline.
Can I speak to a lawyer without paying for the first consultation?
You can have a free consultation, according to seven listed firms. Ask about Paul Cahill's consultation terms before booking, since this list doesn't give them. The firm can still decline your claim after a free discussion. Ask what's included in the consultation, including any records the lawyer wants beforehand. Find out what follows the first assessment as well.
What does a misdiagnosis case need?
You'll need to show what care your provider should have given, with the claim also addressing whether something they did or failed to do caused or contributed to your injury. Ontario lets you start proceedings without having a certificate of merit. You'll still need medical support: in practice, the court's rules require you to serve expert reports on the standard of care and causation. Ask the lawyer how they'd investigate each of those questions.
Do different deadlines apply to children?
Yes. While a claimant is under 18 and has no litigation guardian for the claim, the 2-year period doesn't run. The 15-year ultimate period is also suspended when the claim arises during childhood and the claimant doesn't have a litigation guardian. The court addressed these rules in Wong v. Lui, 2023 ONCA 272. Ask an Ontario lawyer what these rules mean for your child's claim.
How much will a misdiagnosis lawyer charge?
Six listed firms say you can pay through contingency fees. The lawyer takes a share of any recovery, but you don't pay a lawyer's fee if the claim fails. This list doesn't tell you what percentage they'd take. Ask the lawyer to put the fee calculation in writing and explain case expenses separately, including the cost of medical opinions. Check what you'd owe if the firm recovers no money, and do that before signing the agreement.
How long will my claim take?
This list won't tell you reliably how long your misdiagnosis claim will take. The lawyer needs to review records and obtain medical opinions before assessing your claim, which could later reach trial or even an appeal. Ask what needs to happen next to move your file forward. Find out how the firm will update you as your claim progresses, without using another client's published result to judge how long yours should take.
What if my loved one died after a missed diagnosis?
Several listed firms say they handle claims involving wrongful death. Paul Cahill's published results also include a trial he reports winning against an emergency room physician following the death of a mother. That result doesn't tell you whether there's a claim for your own family. An Ontario lawyer can review the records to explain who could bring proceedings. They can check your deadline by working out the applicable limitation period.
Is compensation capped in Ontario?
Ontario doesn't set a statutory cap on economic losses, which include lost income or future care. Non-pecuniary damages have different limits. A judge-made national limit, called the trilogy cap, restricts the compensation you can receive for losses such as pain and suffering. This list doesn't give the amount of that cap. Ask an Ontario lawyer which of your losses might be included in the claim and how these rules would apply to you.
Do I need a lawyer whose office is in Markham?
The offices listed here aren't all local, although one is in Markham. Reyes Tam Law has its office in Markham, but you'll find the others in Toronto or North York, apart from one in Oakville. Check how you'd meet for consultations and later appointments before choosing a firm. An office address tells you nothing about who would handle your file, and it won't show whether the firm has handled similar diagnostic errors.
What should I do before calling a lawyer?
Write down when your symptoms started and when you sought care, making a note of when the diagnosis changed as well. Gather any records and correspondence you already have in one place. Include the date you first suspected that something the provider had done contributed to harm when you write your timeline. The lawyer needs those dates to assess Ontario's discovery rule. You'll need an Ontario lawyer to assess your own situation, since what you've read here is general information, not legal advice.
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Jeremy Syrtash
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