Benign hepatocellular neoplasia occurring in 22 women receiving oral contraceptive steroids but no other known hepatotoxins is reported for the first time from a registry for liver tumors associated with oral contraceptives. A review of recent literature has yielded 45 cases including 3 previously reported by the authors. This striking increase in what were formerly rare primary liver tumors in young women strongly suggests a cause and effect of relationship. Eighteen patients presented with intrahepatic or extrahepatic rupture and hemoperitoneum with hemorrhagic shock due to vascular changes within their liver tumors. Five died as a direct or indirect result of preoperative or postoperative blood loss. The predominant lesions were focal nodular hyperplasia, hepatic adenoma, and hamartoma. Multiple synonymous nomenclature used to describe the histopathology of these tumors is disquieting and requires clarification. For diagnosis, enzyme determinations are not helpful. However, radionucleide liver scans, sonography, and celiac arteriography may be of value. Clinical surveillance must be the primary means for identification of this potentially lethal adverse phenomenon among 50,000,000 oral contraceptive users.