In this study, the effects of gilaburu (Viburnum opulus) juice on colon tumorogenesis were investigated. Eight weeks old Balb-C male mice received subcutaneous injections of 1,2-dimethylhydrazine (DMH) (20mg/kg body weight) once a week for 12 weeks. Both the sham control (group 1) and the DMH control (group 2) groups received drinking water alone, whereas the mice of groups 3 and 4 received gilaburu juice for 30 weeks (started with first DMH injection) and for 18 weeks (started after last DMH injection), respectively. Eighteen weeks after the last DMH injection, all mice were killed and the histogenesis of colon tumors was investigated from the paraffin-embedded sections of colon, which were stained with hematoxylin-eosin. The sites and incidences of tumoral lesions (low-grade dysplasia, high-grade dysplasia, intramucosal carcinoma and invasive carcinoma) were analyzed and compared with control. The results showed that the body weights of the mice were similar in all the groups. No tumoral lesions were found in group 1. Colon tumors developed in all DMH-treated mice (groups 2, 3 and 4). In these groups, the greatest numbers of tumor lesions were detected in the distal colon, followed by the mid-colon and only a few in the proximal colon. There was a reduction in the mean total number of tumor lesion in groups 3 (8.5) and 4 (8.3), when compared to group 2 (11.3). The incidence of invasive carcinoma in group 3 was significantly lower than group 2 (p<0.05). On the basis of these results, we conclude that gilaburu juice may be useful for the prevention of colon cancer at the initiation stage.