Protective effects of diets containing cruciferous seed meals or hulls against chemically-induced colon tumors were examined in male CF1 mice. When commercial crambe meal, autolyzed crambe meal, crambe hulls, high glucosinolate rapeseed meal, or canola meal were fed as 12% of the diets of mice injected with 1,2-dimethylhydrazine, 25-80% of the animals developed colon tumors. Animals fed a soybean meal control diet had a 100% tumor rate. Data suggest that cruciferous seed meals may contain a number of compounds that can exert protective effects against tumor formation and growth.