The anticarcinogenic potential of anethole was studied in Ehrlich ascites tumour (EAT) in the paw of Swiss albino mice. The antitumour activity was evaluated from the cytotoxicity of EAT-cells in the paw and their biochemical changes were determined from nucleic acids, protein, malondialdehyde (MDA) and glutathione (NP-SH) concentrations. Furthermore, the observations on survival rate, tumour weight, its volume and body weight of EAT-bearing mice were made. The EAT-bearing paws were also evaluated for histopathological changes. Additional studies were undertaken on the cytological effects of anethole in order to establish its clastogenic and mitodepressive activity in normal mice. The results obtained in the present study revealed anethole to increase the survival time, reduce the tumour weight and volume and body weight of the EAT-bearing mice. It caused a significant cytotoxic effect in EAT cells in the paw, reduced the levels of nucleic acids and MDA, and increased NP-SH concentrations. The histopathological changes observed after treatment with anethole were comparable to the standard cytotoxic drug cyclophosphamide. The results on the frequency of micronuclei and the ratio of polychromatic erythrocytes to normochromatic erythrocytes showed anethole to be mitodepressive and non-clastogenic in the femoral cells of mice. Our results indicate the anticarcinogenic, cytotoxic and non=clastogenic nature of anethole. Further studies are warranted to explore the mode of action and safety of anethole for its possible use in cancer therapy.