In many patients clinical care in general medical settings is complicated by the presence of psychiatric disorders in addition to the presenting physical symptoms. In the present study the prevalence and type of psychiatric disorders was assessed in relation to the medical diagnostic findings in a general internal medicine out-patient clinic. The Present State Examination, a standardized psychiatric interview, was used to detect psychiatric disorders in 191 newly referred patients. Psychiatric disorders were found to be particularly prevalent among patients with medically ill-explained or unexplained symptoms. The prevalence of psychiatric disorders was 15% for patients with a medical explanation for their presenting symptom, 45% for patients with ill-explained and 38% for those with unexplained symptoms. Approximately 40% of the patients with psychiatric disorders met DSM-III-R criteria for somatization disorder or hypochondriasis, suggesting that these disorders contributed in particular to general medical out-patient referrals.