Microsoft AI outperforms doctors in complex case diagnosis

A new study published in Science shows that Microsoft’s AI diagnostic system correctly diagnosed complex medical cases in a simulation more than twice as often as generalist physicians. This result is a step toward what Microsoft AI’s CEO, Mustafa Suleyman, calls ‘medical superintelligence.’ The system, called MAI-DxO (DxO for short), coordinates several AI agents that act like a panel of doctors. They question a patient, order tests, and debate a diagnosis. In a simulation using complex cases from the New England Journal of Medicine, it was correct 83% of the time. Primary care doctors and general internists, working individually with reference materials, were correct 36% of the time. One note: Cases this complex are usually handled by specialists or physician teams, who weren’t part of the comparison.

Dominic King, vice president of Health at Microsoft AI, told TechCrunch that there is ‘something very substantial and exciting’ here. The biggest challenge in healthcare delivery at the moment is the growing mismatch between demand and supply of medical expertise. In publishing these results, Microsoft joins Google and OpenAI in claiming that its AI can match or outperform doctors. The study’s own data suggests that much of the improvement comes from more powerful underlying AI models, with Microsoft’s orchestration system adding gains on top.

Microsoft tested MAI-DxO with models from several companies, including OpenAI, Google, Anthropic, Meta, and DeepSeek, but its best results came with OpenAI’s GPT-5 and GPT-5.5. Microsoft measured DxO on cost as well as accuracy, meaning the estimated cost of running the AI on each case. On its own with a short, basic prompt, GPT-5 scored 78.9% on complex cases at about $8,400 per case. DxO cut that cost by about $3,000 but raised accuracy by only about four points. On emergency department cases, there was little improvement in either accuracy or cost improvement between GPT-5 on its own and with the assist from DxO.

With GPT-5.5, a newer model released in April 2026, the results split. On complex cases, DxO increased GPT-5.5’s accuracy score from 72% to nearly 87% at a slightly cheaper cost. However, the gains once again didn’t show up on emergency department cases. Both (with and without DxO) scored about 85% at a similar cost. DxO helps most on complex cases and with less capable AI models. Gemini 2.5 Flash, for example, scored 46.4% on its own but nearly 69% with DxO. Even so, the gap between the weaker and stronger models was larger than the boost DxO provided.

Microsoft’s researchers said that accuracy gains naturally shrink as models approach the theoretical maximum. ‘The DxO orchestration helps with the broader challenge of optimization both accuracy and cost,’ a spokesperson added. Suleyman, who leads Microsoft’s effort to build its own frontier AI, told TechCrunch that the company is working with the Mayo Clinic to train a foundation model for healthcare, with release planned for next year. He believes this model will enable the company to ‘make really enormous leaps here,’ and says DxO is part of the foundational infrastructure Microsoft is building to see real breakthroughs in healthcare.