Background: Many of the psychiatric disorders and other medical conditions may affect the sexual function of the patients. The present study aims to investigate the frequency of sexual dysfunctions in male psychiatric patients compared to other medically ill patients. Results: Sexual dysfunction among psychiatric patients (51.2%) was significantly higher than among other medical patients (21%). Among the psychiatric patients, those with schizophrenia (75%) had the highest prevalence rate of sexual dysfunctions. The patients with bipolar disorders, depressive disorders, and anxiety disorders had the following rates respectively: 55%, 45%, and 30%. Among the other medical patients, those with the cardiac diseases (35%) had the highest prevalence rate of sexual dysfunctions. The patients with hepatic diseases, diabetes, urologic diseases, and respiratory diseases had the following rates respectively: 25%, 20%, 15%, and 10%. Prolactin level among psychiatric patients was significantly higher than among the other medical patients, while there was no significant difference between the psychiatric and other medical patients regarding total testosterone level. Conclusion: Considering the significant relative frequency of sexual dysfunctions in psychiatric patients, more emphasis is recommended to be placed on the prevention and proper treatment of these disorders.