OpenEvidence Hits $15 Billion as Doctors Embrace Ad-Funded Medical AI
OpenEvidence hits a $15 billion valuation as nearly two-thirds of US doctors adopt its ad-funded AI, despite accuracy and reliance concerns over patient care.
Summary
OpenEvidence, founded in Miami by Daniel Nadler in 2022, says nearly two-thirds of 1 million US physicians used its ad-funded chatbot, generating more than 42 million prompts in September 2026. Doctors search clinical guidelines and peer-reviewed sources, including the New England Journal of Medicine and Journal of the American Medical Association, for diagnosis and treatment. Eight senior physicians cited lighter workloads; UCSF resident Nina Singh credited faster contextual decisions. Mount Sinai, Memorial Sloan Kettering and NYU Langone embedded it in electronic health records, with NYU's Paul Testa overseeing secure integration. OpenEvidence is adding ambient note-taking.
The startup raised nearly $1 billion over 18 months from Andreessen Horowitz, Blackstone, Thrive Capital and Sequoia, including $250 million in September 2026 at a $15 billion valuation; Mayo Clinic also invested. By end-2025 it had booked $100 million in current and future 2026 ad commitments, with $400 million to $500 million expected by end-2026. OpenEvidence withdrew from the EU and UK in 2026 over the AI Act. Rivals include Wolters Kluwer's UpToDate AI, launched in October 2025 almost two years after OpenEvidence entered, OpenAI's ChatGPT for healthcare and Anthropic's tools. Anthropic also partnered with OpenEvidence across 100 low- and middle-income countries. Investors Mike Vernal of Conviction and Nworah Ayogu of Thrive view physician loyalty as its defense.
Results are mixed. Mayo Clinic's five-case study found accurate, evidence-based recommendations throughout but limited treatment impact; a June Nature paper found OpenEvidence trailed Google's Gemini and OpenAI's GPT on clinical benchmarks. NYU neurosurgeon Eric Oermann cited scant tool-specific research and implementation guidance, while junior doctors risk overreliance. OpenEvidence plans cancer and rare-disease clinical trials within weeks, followed by AI literature-based drug discovery to generate hypotheses, which Nadler expects to dwarf hospital or advertising revenue. Anthropic Claude Science creator Alexander Tarashansky joined its clinical work.
Positives
- More than 42 million prompts in September 2026 demonstrate unusually strong adoption among nearly two-thirds of 1 million US physicians.
- $250 million raised in September 2026 valued OpenEvidence at $15 billion after nearly $1 billion of investment over 18 months.
- $400 million to $500 million in advertising revenue is expected by the end of 2026.
- Mount Sinai, Memorial Sloan Kettering and NYU Langone have embedded OpenEvidence within electronic health records.
- All five Mayo Clinic cases received accurate, evidence-based recommendations, although treatment effects were limited.
- 100 low- and middle-income countries will receive healthcare tools through OpenEvidence's partnership with Anthropic.
Risks & concerns
- A June Nature paper found OpenEvidence underperformed Google's Gemini and OpenAI's GPT on clinical benchmarks.
- OpenEvidence withdrew from the EU and UK in 2026 because of the AI Act, blocking expansion into two major markets.
- Junior doctors may rely excessively on AI before mastering conditions and established treatment options.
- Critics question whether advertising revenue supports the startup's $15 billion valuation.
- OpenAI, Anthropic and Wolters Kluwer are intensifying competition with healthcare-focused AI products.
- Eric Oermann identified limited tool-specific performance research and scant guidance for clinical implementation.