For this evidence-based 2026 list of London misdiagnosis lawyers, we considered published results and practice focus, alongside client reviews and each firm's history.
Our featured firm in London is Diamond & Diamond Lawyers LLP, where Jeremy Syrtash leads the medical malpractice group. Because its history goes back to 1974 and its site covers misdiagnosis, Cohen Highley LLP stands out among the firms we reviewed. Check who handles diagnosis claims and which office would serve you before you call. Find out how you'd pay for fees and medical reports, too. For the limitation rules, see the Ontario malpractice guide.
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)
Best for: Established firm with misdiagnosis coverage
Since its founding in 1974, Cohen Highley LLP has built a long operating history. Misdiagnosis and surgical errors appear on its site. Beyond medical malpractice, the firm also handles work in areas such as family law and housing.
Stood out in our review for its years of experience 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
Medical malpractice and wrongful death appear among the practice areas Wallace Smith Lawyers lists. If a missed diagnosis may have contributed to a death, it's a relevant firm for you to contact. Misdiagnosis and hypoxic-ischaemic encephalopathy (HIE) also appear on its site.
Stood out in our review for 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
Not sure who to call first?
Tell us what happened. A malpractice lawyer who serves London can look at it with you, and it costs nothing.
Best for: Misdiagnosis alongside birth injury concerns
Alongside misdiagnosis, MACKINTOSH PERSONAL INJURY LAW's site discusses concerns about birth injuries. Surgical errors and medication errors appear there too. Your family has several issues to discuss in those areas if the missed diagnosis was part of a wider course of treatment.
Stood out in our review for 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
When you speak to the lawyer, explain the missed diagnosis and the harm you believe followed. As they check the limitation period, they can identify what needs closer review. You generally must start an Ontario claim within 2 years of discovery; don't assume you have 2 years from the treatment date.
Records and medical review
Before the medical review, discuss which records the lawyer needs and how they'll obtain medical opinions. What should the provider have done? The assessment must address that. It must also look at the injury to examine whether the missed diagnosis caused or contributed to it.
Starting the claim
The lawyer must address the applicable filing deadline if the claim goes ahead. To start a claim in Ontario, you don't need an affidavit or certificate of merit. If a minor has no litigation guardian, different limitation rules apply; ask the lawyer to explain what those rules mean.
Expert reports
Under Ontario's court rules, expert reports on the standard of care and causation must be served. Those reports examine how the medical conduct connects to the injury, along with the conduct itself. When your lawyer explains what the reports say, ask which issues the parties still dispute.
Considering resolution
When you discuss a possible resolution or court decision, ask how the medical opinions affect the firm's assessment. Before continuing, ask what it would cost and which losses you're claiming. Economic losses have no statutory cap in Ontario. A national judge-made cap does apply, though, to non-pecuniary damages.
Malpractice claims in London: 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.
If the claim fails under a contingency arrangement, there's no legal fee; otherwise, the lawyer receives a share of what's recovered. This is the arrangement MACKINTOSH PERSONAL INJURY LAW says it offers. You won't find the other listed firms' contingency terms here. You'll also have separate case costs, including the expense of medical records and medical opinions, along with court fees. If the claim doesn't succeed, who carries those expenses, and who advances the money? Ask the firm. Before you sign, get written terms explaining how the lawyer's share is calculated and which expenses could come out of the recovery. You can get a free consultation at all the listed firms. What would further assessment cost you? Ask before proceeding.
You can get a free consultation, according to each of the three listed firms. Contingency work is also mentioned by one firm.
What to bring to your first call
Your symptoms and appointments set out in a written timeline that ends with the eventual diagnosis
Copies of the medical charts and test results you have
A list naming the providers involved in the diagnosis
The referral letters and discharge instructions you received
Letters you've received from the hospital or insurer
Records showing income you lost because of the injury, together with bills
Your notes on when you first linked the missed diagnosis to the injury
Questions to ask a lawyer
1What claims involving this diagnosis have you handled?
2If I have questions, who'll answer them and work on my file?
3Where would your firm manage my claim?
4How did you calculate the limitation deadline that applies to me?
5To assess my claim, which medical records and expert opinions do you need?
6If you offer contingency fees, how would you work out your share?
7If my claim fails, who covers the case expenses?
8What does the free consultation cover?
Choose around the missed diagnosis
Rather than starting with all the firm's services, focus on the medical issue. Misdiagnosis appears on the site of every firm on this list. You still won't know who would handle your file from that. When you explain which diagnosis was missed and when it was eventually made, describe what changed for you afterward. Has the lawyer handled that kind of claim? Ask them.
Don't overlook the office arrangements, either. While Wallace Smith Lawyers and MACKINTOSH PERSONAL INJURY LAW have London offices, Cohen Highley LLP lists London among its locations; the office listed here is in Kitchener. Before arranging to meet, confirm where you'd go and who your regular contact would be. You may recognise a lawyer's name without that lawyer doing the day-to-day work.
Ask how the medical questions will be tested
Before the lawyer decides whether to take the case, ask which charts and test results they'd review and whether they'd also need referral records.
How would they assess what the provider should reasonably have done (the standard of care)?
Ask whether they'd examine if the missed or delayed diagnosis caused or contributed to the injury, and have them explain how they'd assess causation.
Once you've had the first conversation, ask what information could clear up the questions that remain.
To start a claim in Ontario, you don't need an affidavit or certificate of merit. You'll still need medical evidence. Because the court's rules require expert reports on the standard of care and causation to be served, ask who pays for those reports and how the firm arranges them.
Get the fee terms in writing
You can get a free consultation at every listed firm. What does it cover? Ask. If further record review would cost anything, you'll want to know that too. Although MACKINTOSH PERSONAL INJURY LAW says it works on contingency, you won't find the other firms' contingency arrangements stated here. Don't assume they offer the same terms; ask each firm directly.
If the claim fails under a contingency fee, there's no legal fee; otherwise, the lawyer receives a share of a recovery. Find out about case expenses separately. If someone promises a result or pressures you to sign before you understand the agreement, be cautious about proceeding. When you can't get a clear answer about who carries medical-report costs, that's another reason for caution. Although reviews can help you judge communication, they can't forecast how your claim will turn out.
Questions people ask
How long do I have to start a misdiagnosis claim in London?
When you discover the claim, Ontario's basic 2-year limitation period starts. You discover it when you knew, or reasonably ought to have known, about the injury and the provider's contribution to it, along with whether a lawsuit was appropriate. There's also an ultimate limitation period of 15 years. Before relying on your dates, ask an Ontario lawyer how both rules apply.
Can I speak to one of these firms without paying for the first consultation?
You can get a free consultation, according to all three listed firms. Before you send records or request further work, check what the consultation includes. Even if the first conversation is free, you still don't know what pursuing a claim would cost. When you call to discuss the missed diagnosis and limitation period, also ask what you'd be charged for a fuller medical review.
Do these London firms take misdiagnosis claims on contingency?
Contingency is how MACKINTOSH PERSONAL INJURY LAW says it works. Because contingency terms for neither Cohen Highley LLP nor Wallace Smith Lawyers are stated here, you'll need to ask directly. If the claim fails under a contingency arrangement, there's no legal fee; otherwise, the lawyer gets a share of a recovery. You'll need to ask separately who would cover the case expenses.
Does a missed diagnosis by itself establish a malpractice claim?
To assess the medical questions, you need to consider the standard of care and causation. Did the missed diagnosis cause or contribute to the injury, and what should the provider have done? Under Ontario's court rules, expert reports addressing those issues must be served. When you speak to a lawyer, ask how your records could address each question.
Do I need a medical certificate before starting a claim?
To start a malpractice claim in Ontario, you don't need an affidavit or certificate of merit. Under the court's rules, though, you still need expert reports on the standard of care and causation to be served. Don't confuse those separate requirements. When you discuss the medical review your claim needs, a lawyer can explain when the reports must be served.
What limitation rules apply if my child was misdiagnosed?
Until the claimant turns 18, the 2-year period doesn't run if they have no litigation guardian for the claim. If the claim arises while the claimant is a minor without a litigation guardian, the 15-year ultimate period is suspended as well. For this rule, see Wong v. Lui, 2023 ONCA 272. Have an Ontario lawyer check how your child's circumstances fit.
Which listed firm handles claims involving a loved one's death?
Wrongful death appears among the practice areas listed by both Wallace Smith Lawyers and MACKINTOSH PERSONAL INJURY LAW. Because both sites also identify misdiagnosis, they're relevant firms to contact, but you can't tell from that whether either firm would accept your claim. When you speak to an Ontario lawyer, ask who can bring a claim and which limitation rules apply to your family.
How long will a misdiagnosis claim take?
You won't find a fixed claim duration stated for these firms. Before discussing what happens after filing and when you'll get updates, ask which records and medical reports the lawyer will need. You must start your claim by the deadline set by the filing limitation period. Although that deadline doesn't set a timetable for finishing the claim, no firm can promise you a result from the first call.
Is there a cap on compensation in Ontario?
If you're claiming economic losses, such as lost income or future care, Ontario has no statutory cap. The national judge-made trilogy cap limits non-pecuniary damages, which cover losses such as pain and suffering. When you discuss your claim, a lawyer can explain which categories may apply. You can't tell what an individual case could recover from these rules.
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Jeremy Syrtash
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