Neutral fucolipids and fucogangliosides of normal rat liver, normal rat hepatocytes, and rat hepatoma H35 and HTC cells have been compared. H35 cells were characterized by accumulation of a relatively large quantity of a few neutral fucolipids and a major fucoganglioside. HTC cells were characterized by accumulation of several neutral fucolipids and by the absence of fucogangliosides. Those fucolipids which accumulated in hepatoma cells were absent in normal rat liver and normal hepatocytes. Normal hepatocytes and normal rat liver contained a low quantity of fucolipids which migrated differently on thin-layer chromatography from those which accumulated in hepatoma cells. In addition to these qualitative differences, the quantity of total fucose in purified glycolipid fraction was much higher in H35 and significantly higher in HTC cells than that in rat liver. A fucoganglioside which accumulated in H35 cells was tentatively characterized as a fucosylated GM1 ganglioside with the following structure: (formula: see text). The results indicate that anomalous fucosylation on glycolipid may take place in hepatoma cells.