Multiple intestinal neoplasia (Min) mice are a good model for the investigation of the effects of dietary alterations on genetic susceptibility for intestinal cancer. In the current study, nursing dams and their pups were placed on an AIN-93G diet containing either 1 or 6 ppm copper. The pups were maintained on the same concentration of dietary copper after weanling until they were 13-weeks-old. Animals fed copper deficient diets had a significantly (P<0.0003) higher small intestine tumor incidence and a significantly (P<0.04) higher small intestine tumor burden than animals fed adequate dietary copper. Therefore, inadequate dietary copper can increase the spontaneous tumorigenesis that occurs in the Min mouse.