Objective The purpose of this study- wsa to investigate the clinical efficacy and side ef-fects of fluoxetine in the treatment of obsessive compulsive disorder, Methods 36 patients with obsessive compulsive disorder were treated by fluoxetine ( n = 18) and clomipramine ( n = 18 ) and clomipramine ( n =18) ,The efficacy was measured with YALE- Brown Obsessive Compulsive Scale(Y- BOCS), Marks Scale for Compulsions, Phobias, Obsessions and Rituals (MSCPOR), and Hamilton Depression Scale (HAMD). The side effects were determined by the Treament Emergent Symptom Scale(TESS). Results The therapeutic efficacy in fluoxetine group was similar to that in clomipramine(P > 0.05). However the side effects of fluoxetine were lighter than clomipramine, Condusion The results indicate theat both flu-oxetine and clomipramine is effective in the treatment of obsessive compulsive disorder, but fluoxetine showed more advantages for its conventient administration and low daiy dosage and the side effects of it were light.