Ethanolic extract of Hydrastis canadensis has been tested for its possible anti-cancer potentials against p-dimethylaminoazobenzene (p-DAB) induced hepatocarcinogenesis in mice. Mice were chronically fed p-dimethylaminoazobenzene (p-DAB) and phenobarbital (PB), two hepato-carcinogens for 1, 2, 3 and 4 months, respectively, and were divided into sub-groups: i) fed normal low protein diet (Gr. I, normal control); ii) fed diet mixed with 0.06% p-DAB at a daily dose of 165 mg/kg b.w. per mouse plus 0.05% PB plus 0.06 ml 90% alcohol (vehicle of the crude extract) (Gr. II, carcinogen treated); iii) fed diet mixed with p-DAB and PB at the same daily dose plus crude extract of Hydrastis canadensis (Gr. III, drug treated). Several biochemical parameters like acid and alkaline phosphatases, alanine amino-, aspartate amino-, and gamma glutamyl-transferases, lipid peroxidation, reduced glutathione content, lactate dehydrogenase, catalase and glucose-6-phosphate dehydrogenase activities and electron microscopy of liver in different groups of treated and control mice were studied. A critical analysis of results of these studies suggested anti-cancer potentials of the drug suitable for use as a supportive complementary medicine in liver cancer.