The authors report results of investigation of 77 male patients with syphilis; 45 of them also had HIV. The authors found high rates of mental problems in this group, with prevalent adjustment disorders. Patients with both syphilis and HIV showed higher rates of substance-related disorders. They also showed an association between social maladjustment in their history, accompanied by mental and behaviour disorders, and presence of a mental disorder at the time of investigation, specifically social maladjustment.