Objectives Many features of fibromyalgia syndrome (FMS) resemble those of posttraumatic stress disorder (PTSD). The goal of this study was to investigate the comorbidity of FMS and PTSD in a cohort of men following an intensive, initial, defined traumatic event. Methods One hundred twenty-four males (55 patients with PTSD, 20 patients with major depression, and 49 controls) were evaluated for the presence of FMS. The major traumatic events in all PTSD patients were combat-related. Each individual completed questionnaires characterizing his disease, disabilities, and quality of life. Results Forty-nine percent of PTSD patients, compared to 5% of major depression patients and none of normal controls, fulfilled the American College of Rheumatology criteria for FMS (P