Aim of the work: The evidence for specific soybean-derived compounds having a suppressive effect on carcinogenesis in animal model systems is created, the anti-carcinogenic potential of soybean was studied against colon cancer. Colon cancer has been induced by dimethylhydrazine (DMH).
 Material and methods: The DMH was dissolved in physiologic saline and the animals were given subcutaneous injections once weekly for 16 weeks. The possible preventive effects of  soybean on Dimethylhydrazine-induced colon tumors in male Sprague Dawley rats was investigated. Albino rats were divided into four groups.  control group, control soybean powder group, DMH-treated colon cancer group and the fourth group treated with  soybean powder+DMH.
 Results: In the studied groups the colon was examined macroscopilly to calculate  the number of polyps appeared in each colon. The histological and ultrastructural studies included the alternations in different component of the colon. The macroscopical examination showed that the group which was given the soybean alone showed no polyps. On the other hand the group that was given the carcinogenic agent alone expressed a high number of polyps. The histological and ultrastructural studies showed that colon cell structure of carcinogenic treated animal groups underwent cell proliferation, focal cell damage with certain nuclear changes, abundance of fibrous tissue and lymphocytic infiltration, while the group given soybean as a preventive agent expressing less number of colon polyps, and induced a moderate changes of different degrees. Conclusion: It is clear that soy bean component showed a good protective effect against the colon cancer.