MedReason: Eliciting Factual Medical Reasoning Steps in LLMs via Knowledge Graphs

Juncheng Wu, Wenlong Deng, Xingxuan Li, Sheng Liu, Taomian Mi, Yifan Peng, Ziyang Xu, Yi Liu, Hyunjin Cho, Chang-In Choi, Yihan Cao, Hui Ren, Xiang Li, Xiaoxiao Li, Yuyin Zhou


Abstract
Medical tasks such as diagnosis and treatment planning require precise and complex reasoning, particularly in life-critical domains. Unlike mathematical reasoning, medical reasoning demands meticulous, verifiable thought processes to ensure reliability and accuracy. However, there is a notable lack of datasets that provide transparent, step-by-step reasoning to validate and enhance the medical reasoning ability of AI models. To bridge this gap, we introduce **MedReason**, a large-scale high-quality medical reasoning dataset designed to enable faithful and explainable medical problem-solving in large language models (LLMs). We utilize a structured medical knowledge graph (KG) to convert clinical QA pairs into logical chains of reasoning, or “thinking paths”, which trace connections from question elements to answers via relevant KG entities. Each path is validated for consistency with clinical logic and evidence-based medicine. Our pipeline generates detailed reasoning for various medical questions from 7 medical datasets, resulting in a dataset of **32,682** question-answer pairs, each with detailed, step-by-step explanations. Experiments demonstrate that fine-tuning with our dataset consistently boosts medical problem-solving capabilities, achieving significant gains of up to **7.7%** for DeepSeek-Ditill-8B. Our top-performing model, MedReason-8B, outperforms the Huatuo-o1-8B, a state-of-the-art medical reasoning model, by up to **4.2%** on the clinical benchmark MedBullets. We also engage medical professionals from diverse specialties to assess our dataset’s quality, ensuring MedReason offers accurate and coherent medical reasoning. Our data, models, and code will be publicly available.
Anthology ID:
2026.groundlm-1.1
Volume:
Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Yimu Wang, Yee Man Choi, Di Wu, Siqi Ouyang, Mozhgan Nasr Azadani, Yi R. (May) Fung
Venues:
GroundLM | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1–17
Language:
URL:
https://aclanthology.org/2026.groundlm-1.1/
DOI:
Bibkey:
Cite (ACL):
Juncheng Wu, Wenlong Deng, Xingxuan Li, Sheng Liu, Taomian Mi, Yifan Peng, Ziyang Xu, Yi Liu, Hyunjin Cho, Chang-In Choi, Yihan Cao, Hui Ren, Xiang Li, Xiaoxiao Li, and Yuyin Zhou. 2026. MedReason: Eliciting Factual Medical Reasoning Steps in LLMs via Knowledge Graphs. In Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026), pages 1–17, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
MedReason: Eliciting Factual Medical Reasoning Steps in LLMs via Knowledge Graphs (Wu et al., GroundLM 2026)
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PDF:
https://aclanthology.org/2026.groundlm-1.1.pdf