Members of Childrens Cancer Study Group and the Pediatric Division of the Southwest Oncology Group conducted a study of chemotherapy for children with malignant liver tumors. All patients received vincristine, cyclophosphamide, Adriamycin and 5-fluorouracil in 6 weekly cycles for one year. Surgical resection and irradiation were employed when indicated. Between January 1976 and August 1978, 62 patients were entered on study; one was rejected for a protocol error, and ten had inadequate trials of chemotherapy, dying within one month of entry. The median time on study for all patients was 12 months. Twenty-four patients had no measurable disease following surgical treatment and chemotherapy was employed as adjuvant treatment; 20/24 (83%) remain relapse-free from 8-42+ months, (median, 30 months). In 27 patients, residual measurable disease was available to determine the response to chemotherapy. The response rate was 12/27 (44%), lasting 3-45 months (median, 18 months). The median follow-up of all survivors is 30 months. Hematologic toxicity was significant, particularly during the initial courses of chemotherapy; 28/57 patients developed severe toxicity which was fatal in three. The results from the current study were compared to those from a previous one initiated in 1972, in which actinomycin D, vincristine, and cyclophosphamide were given in sequence, one during each month for one year. Although the population of the two studies was not identical, there was a difference in the response rates (P = 0.02), relapse-free interval (P = 0.008), and survival (P = 0.003). The most striking improvement was seen in the patients with Group I disease, there were 7/11 relapses in the first study and 1/16 in the current one.