OBJECTIVE: A substantial number of patients with psychiatric disorders consult primary care physicians for comprehensive health care; however, the diagnosis and effective treatment of psychiatric disorders are deficient in primary health care. The aim of this intervention study is to assess the pre- and post-psychiatric training knowledge of primary care physicians. METHOD: The setting of this study was Buraidah Mental Health Hospital. The research design consisted of a pre- and post-test comparison of physicians' responses (n = 70) with a control group (n = 40). The instrument includes a Knowledge Test comprised of 50 questions on primary care psychiatry. RESULTS: There were no significant differences between the intervention and control groups with regard to several confounding sociodemographic variables, but physicians' age and duration of medical practice were significantly higher in the control group. There were significant differences between knowledge of intervention and controls prior to psychiatric training and this difference was further highly significant post-psychiatric training. The gain in knowledge of intervention group post-psychiatric training was highly significant as compared to pre-test knowledge but there was no difference in the knowledge of the control group. CONCLUSION: Psychiatric training courses can enhance physicians' knowledge in clinical psychiatry with possible psychiatric implications, including early diagnosis and better treatment of primary care patients with psychiatric problems.