Abstract: The effect of fish oil on 7,12-dimethylbenz(a) anthracene (DMBA) - induced liver tumors in toads Bufo regularis was investigated. Feeding toads with DMBA 0.5 mg/toad twice weekly for 14 weeks, induced liver tumors (hepatocellular carcinomas) in 32 % of the treated animals. No tumors were detected in toads received DMBA plus 0.1 ml fish oil. Biochemical estimation of several parameters; total lipids, cholesterol, triglycerides, glutamic pyruvic acid transaminase (GPT) and glutamic oxaloacetic acid transaminase (GOT), demonstrated a significant effects of fish oil on the alterations induced by DMBA. The obtained results collectively revealed the anticancer activity of fish oil as well as its pronounced ameliorative effect against the toxic effects of DMBA on the haematochemical parameters in toads Bufo regularis.