In order to perform resections of tumors at critical sites in the liver in young children, liver resections in cardiac arrest and deep hypothermia under cardiopulmonary bypass have been developed. We report our experience with liver resection under cardiopulmonary bypass in three children with hepatoblastoma. In the first child the operation was performed under cardiac arrest and, the other two children were operated on under "low flow" conditions. The periods under cardiopulmonary bypass circulation were well tolerated. Extended right liver resections with vascular reconstructions were performed. The postoperative increase of liver enzymes was moderate. The increase in GOT was between 100 and 200 U/l. In spite of the extended tumor growth, reasonable long-term results were achieved by resection in combination with chemotherapy. One child has been living 8 years and another 10 months without tumor recurrence. The third child died due to sepsis during adjuvant chemotherapy, after she had recovered well from liver resection.