The modulatory effect of browned yam flour diet, a dietary, staple in south-western Nigeria, on carbon tetrachloride (CCl4)-mediated lipid peroxidation and on the activities of liver microsomal and cytosolic enzymes was studied in male rats. Browned yam flour diet fed at the level of 25% and 50% to rats for 5 weeks significantly reduced the lipid peroxidation induced by CCl4 (0.5 ml/kg/wk) administered two weeks after starting the animals with the diets. The diets elicited 62% and 79% reductions in CCl4-mediated peroxidation, respectively, in the absence of exogenously added oxidants. The activities of microsomal aniline hydroxylase (AH), aminopyrine-N-demethylase (APD), pentoxyresorufin-O-dealkylase (PROD) and cytosolic GSH S-transferase (GST) were increased when rats were fed the 25% or 50% browned yam flour diets. Browned yam flour fed at the level of 25% to rats decreased the CCl4-mediated reduction in the activities of microsomal AH, APD, PROD and GST by 64%, 28%, 58% and 25%, respectively, and by 82%, 48%, 83% and 55% when rats were fed with 50% of the diet. The results suggest that browned yam flour diet could protect against chemically-mediated lipid peroxidation and tissue damage possibly by scavenging chemically generated reactive species and enhancing carcinogen-detoxifying system.