OpenAI releases MentalHealthBench, an open benchmark for AI in mental-health conversations

2026-09-23★★★after cutoffbenchmarkOpenAIconfidence: medium

On Sept 23, 2026 OpenAI released MentalHealthBench: 1,215 synthetic mental-health conversations with 5,262 rubric criteria written with 80+ licensed clinicians from 22 countries. It scores safety, context-seeking, user agency and actionable guidance. Reported top scores: GPT-6 Astra 57.3%, GPT-6 Sol 53.9%, Claude Opus 5.5 52.4%, and GPT-4o 32.1%.

Key facts

1,215 conversations, 5,262 rubric criteria, 80+ mental-health experts from 22 countries
Scenario mix: 53.5% non-acute, 18.2% high-acuity, 28.3% emergency
10 behavioral axes, incl. context seeking, empathy, urgency calibration and reality testing
Reported scores: GPT-6 Astra 57.3%, GPT-6 Sol 53.9%, Claude Opus 5.5 52.4%, GPT-6 Luna 50.2%, Muse Spark 1.3 47%, GPT-4o 32.1%, Gemini 2.5 Pro 29.5%
Critics (e.g. NxCode) note that rubric scoring of single conversations cannot measure long-run outcomes for users

What happened

OpenAI published an expert-written, rubric-graded benchmark for mental-health conversations, extending its HealthBench approach. It was released as an open benchmark, and the launch results compare OpenAI models with Claude, Gemini and Meta's Muse Spark.

Why it matters

Mental-health use of chatbots was a major 2025–2026 safety and litigation topic, and this gives labs and regulators a shared measure. The scores are OpenAI-reported and, per secondary sources, OpenAI models lead. Treat them as vendor results (confidence: medium, since openai.com was not directly readable).

Changelog

2026-09-29: created

Related events

2026-09-03OpenAI releases GPT-6 Astra, its first GPT-6 model ★★★★★
2026-09-22Anthropic releases Claude Opus 5.5 — Fable-5.1-level performance at $4/$20, first model of the Claude 5.5 family ★★★★★

Sources (4)

id: 2026-09-23-openai-mentalhealthbench · updated 2026-09-29 · open in the interactive timeline