From May 1978 to August 1988, 15 children with a primary malignant liver tumor received radiation therapy as part of their management at the Institut Gustave-Roussy. Age ranged from 4 months to 13 years. The male to female ratio was 1.5. Eleven patients had a histologically proven hepatoblastoma, two a hepatocellular carcinoma, and histology was not documented in two. Resection of the primary liver tumor was performed in nine cases, and all patients also received sequential chemotherapy, generally preoperative and alternating vincristine, doxorubicin, cyclophosphamide with vincristine, cyclophosphamide, and cis-platinum. Radiotherapy was performed postoperatively in eight incompletely resected patients. Six of eight are alive and free of disease 4-83 months following treatment (median 39 months) and 11-98 months since diagnosis (median 45 months). All but one were treated to limited fields to a total dose of 25-45 Gy (median 40 Gy). One patient became resectable by a combination of 24 Gy to the whole liver and concomitant 5FU and Cis-Platinum and remains with no evidence of disease 68 months following radiation therapy. Of four unresectable primaries, only one was controlled by radiotherapy. Neither of two children with pulmonary metastases were controlled by whole lung irradiation to a dose of 18 and 20 Gy, respectively, and one still remains stable 41 months after resection of a residual metastatic nodule. Neither of two hepatocellular carcinomas were controlled by doses up to 40 Gy. This small series suggests that in hepatoblastoma, radiotherapy to a total of 25-45 Gy fractionated doses, combined with chemotherapy, can play a role in selected inoperable children and also in those with minimal postoperative residues below 2 cm. It also indicates that in hepatocellular carcinoma, radiotherapy is ineffective in this dose-range.