Somatization disorder is a condition characterized by multiple unexplained complaints. This study was done to determine the prevalence of somatization disorder in a family practice office setting, to characterize the patients so affected, and to assess their impact on the practice. A sample of ill patients was interviewed, of whom 6 (5 percent) had definite somatization disorder and another 4 (4 percent) had borderline somatization disorder (ten or more symptoms). All were women, and they were more likely than controls to live in households with children but no spouse (P less than .01). They were also more likely than their unaffected counterparts to be from the lowest two social classes (P less than .01). Compared with matched controls, their rate of office visits and charges incurred was about 50 percent greater (.58 visits per month vs .41 visits per month; $23.28 per month vs $14.44 per month). Their charts were thicker (7 cm vs 3.6 cm) and heavier (3076 g vs 1843 g) and had more diagnoses (85 vs 51) than controls. The physicians of the somatizers were significantly less satisfied with the care rendered to them than to the controls (P less than .01). This study demonstrates that somatization disorder is a prevalent, expensive, and difficult problem for family physicians.