As determined in the U.S. Third National Cancer Survey, 1969--71, the incidence of ovarian cancer was 60-70% higher in women who had never married than in those who had. This relationship was present in both whites and blacks and in all age groups over 25 years. Among ovarian epithelial tumors, those for which the incidence rates between never-married and ever-married women differed most were endometrioid and clear cell tumors. The incidence of tumors of germ cell and sex cordmesenchyme origin, however, showed no relationship to marital status.