The authors evaluated alternative criteria for somatization disorder in 277 female and 129 male psychiatric inpatients. In women, the diagnosis of somatization disorder based on DSM-III criteria was highly concordant with the diagnosis of Briquet's syndrome based on Guze's original criteria. There was familial aggregation for Briquet's syndrome in women but none among individuals of either sex who had somatization disorder without the full Briquet's syndrome. In men, the diagnosis of somatization disorder was rarer and less stable than in women. The findings show that somatization usually has a different clinical picture and different familial antecedents in men than in women.