Al-Razi heavily emphasized the importance of accurate and detailed clinical observation as the foundation of diagnosis. He documented symptoms, patient histories, and the progression of diseases to understand their nature and cause.

Al-Razi employed various physical examination techniques, including palpation, percussion, and auscultation (although less documented). He used these techniques to assess the condition of internal organs and identify abnormalities.

Al-Razi had an extensive knowledge of pharmacology and employed a wide range of herbal remedies and medications. He documented the properties and uses of different drugs and carefully monitored their effects on patients. Al-Razi was interested in the preparation of medicines and included details regarding this in his medical writings.

Al-Razi recognized the importance of diet in maintaining health and treating diseases. He provided dietary recommendations based on the patient's condition, the disease, and the individual's constitution.