After a pilot phase in 1988 the liver tumour study HB-89 of the German Society of Pediatric Oncology and Hematology (GPOH) was started on January 1st 1989. It comprises the malignant epithelial liver tumours of childhood--hepatoblastoma and hepatocellular carcinoma. The objectives of the study are 1. to reduce surgical complications and incomplete tumour resections by restricting the primary operation to a lobectomy of the liver in case of small tumours or to a biopsy in case of extended disease, and 2. to reduce the size of large tumours by means of chemotherapy for subsequent resection. The tumourreductive and adjuvant chemotherapy consists of the combinations of ifosfamide, cisplatinum, adriamycin (IPA) and cisplatinum plus adriamycin as continuous infusion (PA-cont). Up to December 31st 1991 a total of 78 pediatric liver tumours were registered, 51 of those hepatoblastomas and 10 hepatocellular carcinomas. 19 (37%) hepatoblastomas were resected at primary operation (stage I and II). After chemotherapy 24 (83%) of 29 primarily inoperable hepatoblastomas (stage III and IV) became resectable, one child received a liver transplant. At the time all hepatoblastoma patients of stages I and II and 20 (69%) of stages III and IV are in remission, the overall remission rate is 81% (39/48). Seven patients with multifocal hepatoblastoma had an unfavourable outcome, only two are free of tumour. Of 10 patients with a hepatocellular carcinoma only three with a primary complete tumour resection are disease free. The IPA and PA-cont therapies were highly effective on hepatoblastomas (96%), but not on hepatocellular carcinomas.(ABSTRACT TRUNCATED AT 250 WORDS)