A double-blind trial was carried out to assess the efficacy and safety of fluvoxamine, a selective serotonin reuptake inhibitor, in comparison with clomipramine, a classical tricyclic antidepressant, in the treatment of obsessive-compulsive disorder. A total of 26 individuals with obsessive-compulsive disorder and with no comorbid disorders at baseline were included in the study. The obsessive-compulsive disorder symptom severity was rated using the Yale-Brown Obsessive-Compulsive Scale and the Clinical Global Impression Scale. The primary efficacy measures indicated an equal improvement in the two groups (38% in the patients taking fluvoxamine and 40% in those taking clomipramine, as compared with baseline values), but onset was faster in the clomipramine group. Side effects, in particular anticholinergic side effects, were more prominent in the clomipramine group. The present double-blind trial confirms an equal efficacy of clomipramine and fluvoxamine in obsessive-compulsive patients. Although clomipramine had a faster onset, fluvoxamine was better tolerated, so that it seems more suitable for long-term treatment of obsessive-compulsive patients.