Although most children who die of liver malignancies do so as the result of complications of pulmonary metastases, little has been published regarding the efficacy of surgically excising such lesions. To the 12 previously reported cases of children who have undergone excision of pulmonary metastases of hepatic tumors, are added 5, 4 with hepatoblastoma and 1 with hepatocellular carcinoma. Total excision of a primary hepatic tumor leads to survival much more frequently than does incomplete excision. No patient had metastases at diagnosis. The length of time between resection of the primary tumor and the development of pulmonary disease resistant to chemotherapy is available for 9 of the 17 children; it was under 6 months for the 2 who died but over 6 months for the 7 who survived. Postoperative alpha-fetoprotein (AFP) levels accurately predicted the development of metastases in our 5 patients. Resection of metastases benefitted the 4 whose AFP levels had declined to less than 25 ng/mL following initial chemotherapy and who underwent operation before their levels increased above 1,000 ng/mL. They are alive and free of disease 4 to 83 months following excision of their lesions. Resection did not benefit the 1 nonsurvivor whose AFP level fell only to 5,000 ng/mL before beginning to increase, eventually reaching 58,000 ng/mL at the time of operation. Incomplete resection of metastases unresponsive to chemotherapy predictably leads to death. Multiple thoracotomies were successful in achieving the long-term survival of 4 children in this series.(ABSTRACT TRUNCATED AT 250 WORDS)