Hepatoblastoma is a rare neoplasm of infants and children only recently documented in association with hereditary adenomatous polyposis of the colon [Kingston et al., 1983]. We report four children with hepatoblastoma from four unrelated families with Gardner syndrome (GS). One child, now 19 years old, survived after a resection of a hepatoblastoma in infancy and recently was found to have GS. He has an associated odontoma and pigmented ocular fundus lesions, both of which have been shown to be clinical markers of GS. Many individuals in these four GS families, both affected and at risk, have osteomatous jaw lesions and pigmented ocular fundus lesions. A search for colonic polyps should be made in families of infants and children with hepatoblastoma. If the child survives, he or she should be monitored for the later appearance of colonic polyps. The finding of jaw lesions and/or pigmented ocular fundus lesions in relatives at risk are indications of the possible presence of the GS gene.