Forty-seven children treated in various Polish centers between 1985 and 1995 for primary malignant liver tumors were retrospectively analyzed. Hepatoblastoma (HB) prevailed--it was found in 39 cases. There were 6 hepatocarcinoma (HCC) cases and 2 cases of undifferentiated sarcoma (UDS). In 44% of HB patients the tumor involved both liver lobes. 18% of children with HB presented with pulmonary metastases at diagnosis. Chemotherapy was applied in 92% of cases (preoperatively in 67%). Tumor resection was performed in 56% of HB patients. Overall survival of patients with hepatoblastoma was 43.6%, while it was 50% for hepatocarcinoma and 100% for undifferentiated sarcoma (2 cases only). Mean observation time was 58 months. The hepatoblastoma subgroup, being the largest (83% of all cases), was analyzed separately for prognostic factors. Completeness of tumor excision strongly influenced survival. Involvement of both lobes of the liver and multifocality of the tumor were other adverse prognostic factors.