The effect of Ganoderma lucidum (Polyporaceae) extract on initiation and promotion of liver preneoplastic lesions in chemical carcinogenesis were examined in male rats. Male Fisher 344 rats, 8 weeks old, were injected i.p. with diethylnitro-samine(DENA` 200 mg/kg) as an initiator and were fed on diet containing 0.02%-acetaminofluorene (2-AAF) as a promoter for 2 weeks (group 1, 2` 2-4 week) and were fed on basal diet (group 3 and 4). The rats in test groups(group 1 and 3) were fed on diet containing 0.1% of Ganoderma lucidum extract for 6 weeks (2-8 week).