Background: Widespread irrational medical prescription adversely affects the outcomes of patient health and medical services. Aim: This study aims to investigate the determinants of medical prescription behavior of family physicians in Erzurum Province. Materials and Methods: This cross-sectional descriptive study was conducted during AugustuDecember 2016 on a voluntary sample of 191 out of 234 physicians (81.6%) working at family health centers in the districts of Erzurum. Physicians were visited at their workplaces, and data were collected using a self-administered and structured, 45-item questionnaire. Results: The mean age of the physicians was 34.7 7.9 years, and 70.7% (n = 135) of the participants were males. About 83.8% (n = 160) of physicians responded "yes" or "sometimes" to the question "Do you prescribe medicine on demand of the patients" The two most important factors that affected the prescribing behavior of the participants were the pharmacology lectures attended during medical education (50.8%) and the prescribing experience acquired during clinical internship (46.0%). Presentations given by the representatives of drug companies, in-service training programs after graduation, and Internet/mobile phone applications had the lowest rate of contribution as behavioral determinants. The participants perceived having sufficient information in the areas of indication for use (77.5%) and daily dose (72.8%). Only 4.2% of participants deemed their knowledge of medication costs sufficient. Pharmacology lessons were found to be more effective in the prescribing behaviors of the physicians who had less than 10 years of professional experience (Chi-square = 12.131; P = 0.002). Conclusion: Rational medical prescription continues to be a trouble among family physicians. The study findings suggest a substantial knowledge gap in participating physicians occurring after graduation and clinical internship training, in the areas of costs of medicine and rational medical prescribing.