Fibromyalgia is a chronic illness characterized by widespread pain, sleep disturbance, tender points, and resistance to treatment. Amitriptyline has shown some efficacy in treatment of fibromyalgia. The purpose of this study was to evaluate the effectiveness of paroxetine on fibromyalgia. Paroxetine, a specific serotonin reuptake inhibitor, was compared to amitriptyline in the treatment of 68 outpatients with fibromyalgia disease. Patients were randomly assigned to 6 weeks of treatment with paroxetine or amitriptyline. Paraxetine was found to have abetter therapeutic effect comparable to that of amitriptyline; However, the paroxetine treatment group had a lower incidence of anticholinergic effects and treatment related side effects. Five amitriptyline-treated patients had to discontinue the study because of serious side effects, while in the paroxetine treatment group 2 patients had to discontinue the study due to side effects.