Two cases of fibrolamellar carcinoma of the liver are reported in young female patients of 12 and 21 years of age. Small amounts of perinuclear alpha-fetoprotein were found, unrelated to hyaline globules, as well as alpha 1-antitrypsin in a periglobular fashion in isolated cells. Ferritin was present in a large number of cells. Ultrastructurally, the well differentiated nature of the neoplasm was substantiated by previously unreported findings such as intercellular lumina analogous to bile canaliculi and peroxisome-like bodies containing a central crystalloid. Filamentous material resembling Mallory's type of hyaline was also found. We conclude that both immunohistochemical and ultrastructural features reflect a high degree of differentiation.