The American College of Surgeons’ survey data on 378 female and 165 male cases of primary liver tumors reported by 477 hospitals in the United States during 1970–1975 are presented. In males, 91.5% of the tumors were malignant, confirming the rarity of benign liver tumors in males. Among females, 43.9% were malignant and 56.1% were benign. Of the 212 benign tumors, 96 were hepatic cell adenomas and 58 were focal nodular hyperplasias. A positive history of oral contraceptive use was found in nearly half of all tumors, 65% of benign tumors, 74% of hepatic cell adenomas, and 74% of focal nodular hyperplasias. High frequencies of benign tumors were observed in the age group 20–30 yr. More than 80% of the tumors in this age group were found in oral contraceptive users. Symptomatology was more severe among users. No case of intraperitoneol bleeding was observed in nonusers. The findings confirm the suggested association between use of oral contraceptives and hepatic cell adenomas and focal nodular hyperplasias.