Öz Purpose: The aim of this study is to determine the knowledge and behaviour of the physicians about rational drug use in Adana. Materials and Methods: In this descriptive crosssectional study, a questionnaire consisting of 21 questions asking the knowledge and behaviours about rational drug use were administered in 353 physicians. Thus, we have reached 64.2% of the target population. Results: It was found that while prescribing, 96.3% of the group used drug informations, 60.3% of them used diagnosis and management guidelines, 59.4% used internet, 39.9% read short drug informations frequently. 60.1% of them told that they are well-knowledged about the indications of the drugs, 52.4% about the posology and administration, 48.7% about pharmacological properties, 46.7% about contraindications, 49% about side effects, 48.1% warnings and precautions, 47% about pregnancy and pediatric use, 41.9% about the bioequivalence. 47.6% of the never prescribed a receipt without physical examination and asked the patient about medical history. According to 51% of the physicians, the drug information they gave was enough, 60.6% of them did not report the adverse events, 46.2% did not report adverse events because of work intensivity. Of 44% were knowledged about pharmacovigilance, 73.4% of them did not know the Pharmacovigilance Center of Turkey. Conclusions: Physicians in hospitals were sensitive about rational drug use, prescribing and informing the patient. However, they were not enough sensitive about adverse reaction reports and pharmacovigilance. I