Objective The few psychodermatological studies of primary psychiatric populations so far suggest that parasitic-infectious skin diseases are the most common dermatological comorbidity in more than 70% of psychiatric patients, which should be studied here in a large data bank outside dermatological treatment facilities. Methods In a descriptive-explorative and retrospective study, more than 17,000 patients with primary psychiatric disorders were examined to investigate dermatological comorbidities. Results The proportion of patients with primary mental disorders and additional dermatological disease was 1.24% (n=212). Here, psoriasis (35.4%) and atopic dermatitis (22.6%) were the most frequent dermatological diseases among these 212 patients. Infectiousparasitic skin diseases were present in 13.2% of comorbid patients. The most common mental disorder was a depressive illness, seen in 42.5% (n=90) of patients. Conclusion Our results confirmed the frequent association of depression with psoriasis and atopic dermatitis, indicating the need for the early detection and treatment of such comorbid patients. In contrast, psychiatric inpatients do not appear to suffer from predominantly infectious-parasitic dermatoses.