Al-Razi was appointed as the chief physician of the hospital in his hometown of Rayy. This marked a significant step in his medical career and provided him with extensive clinical experience.

Al-Razi's reputation led to his appointment as the chief physician of the Al-Mu'tadidi Hospital in Baghdad, a prestigious and important medical center. His role involved managing the hospital, treating patients, and overseeing the training of medical students. The exact dates of his tenure are subject to scholarly debate, but it generally spans this period. This hospital also served as an important center for medical research.

During his time as a hospital director, al-Razi made meticulous clinical observations and documented his findings. These observations formed the basis of many of his medical treatises, including his detailed descriptions of diseases and their treatments.