Diallyl sulfide (DAS), a flavoring compound derived from garlic, is considered to have cancerchemopreventive potential in experimental animals and humans. This study was designated to examinepossible chemopreventive effects of DAS on colon carcinogenesis using genetically engineered transgenicApcMin/+ mice, a well-established animal model for familial adenomatous polyposis (FAP) and sporadiccolorectal cancer. Male C57BL/6J-ApcMin/+ mice were divided into three groups. Animals of group 1 wereplaced on the basal diet (AIN-76A) as non-treated controls. Animals of groups 2 and 3 were given DAScontainingdiets (in doses of 100 and 300 ppm, respectively). All mice were sacrificed at the end of week10 of the experiment. Histopathological investigation revealed that the incidence of colonic polyps wasdecreased dose-dependently by 19% (13/16) in group 2 and by 32% (13/20) in group 3 compared to the100% incidence (10/10) in group 1. The multiplicity of colonic polyps per mouse was also slightly decreasedby DAS treatment (1.88±0.35 in group 2 and 1.63±0.36 in group 3) compared to 2.00±0.39 in group 1. Onthe other hand, there were no significant differences in the numbers of total polyps per mouse in the smallintestine between the groups. Taken together, we suggest that DAS may exert promising inhibitory effectson colon carcinogenesis in the transgenic ApcMin/+ mice.