PIP: Primary benign liver tumors are rare, however, the diagnosis should be considered in young women with right upper quadrant pain and an enlarged liver, expecially if they are taking oral contraceptives. These tumors are best resected promptly because of the frequency of spontaneous rupture. In the case reported, the patient was a 29-year-old housewife, gravida 1, para 1. Diarrhea of 8 years' duration was complained of. Anticholinergic sedatives and birth control pills were being used, and tetracycline, 250 mg daily, had been taken for acne for 5 years. A tender liver mass was palpable 3 cm below the ribs. Upper GI X-rays showed a mass displacing the small bowel. Liver scan showed an enlarged right lobe. At surgery a large encapsulated tumor of the right lobe of the liver was found. Subtotal hepatic lobectomy and cholecystectomy were done. The laboratory diagnosis was vascular liver tumor, type undetermined. Photographic reproductions illustrate histologic findings. Following surgery the diarrhea ceased and the patient has remained well. Hepatic angiography, although not done in this case, is considered to be a useful diagnostic method. Percutaneous liver biposy is contraindicated due to the vascular nature of these tumors.