Tabriz University of Medical Sciences Medical Journal of Tabriz University of Medical Sciences 2783-2031 47 3 2025 08 19 A reappraisal of a pioneering work in the history of Medicine: An introduction to Muhammad ibn Zakariya al-Razi’s treatise al-Obneh 241 246 10.34172/mj.025.34067 EN Alireza Bagherzadeh Karimi https://orcid.org/0000-0002-8937-2577 Reza Mohammadinasab https://orcid.org/0000-0001-7958-7390 Journal Article 10.34172/mj.025.34067 2025 06 07 2025 06 09 This letter introduces Risalah fi al-Ubnah, a remarkable treatise by the ninth-century Persian physician Muhammad ibn Zakariya al-Razi, which offers a scientific analysis of gender identity and sexual orientation. Translated by Franz Rosenthal and published in 1978, this work represents one of the earliest systematic attempts to explain biological aspects of gender and sexual differences in medical history. Employing a rational and evidence-based approach, al-Razi addresses topics considered taboo in his era, drawing on clinical observations. The treatise holds significant value for the history of medicine, gender studies, and medical ethics, serving as a vital resource for interdisciplinary research and contemporary discussions on gender identity. This letter aims to highlight its importance and encourage critical re-examination within modern frameworks.