Objective: Colon cancer is one of the most common forms of cancer in the world. Experimental animal models of the neoplastic diseases are important in understanding etiological and pathophysiological processes. 1,2-dimethylhydrazine (DMH) is a potent colon carcinogen and commonly used in the studies investigating the effects of diet on colon cancer. In this study, the relationship between 1,2-dimethylhydrazine and tumor development were investigated. Material and Methods: Eight-week old, fifty balb/c male mice were used for our experiments and treated with subcutaneous DMH solution (20 mg/kg) once weekly throughout a period of 12 weeks. After the end of the last DMH injection, they were sacrificed in sixth (group A), twelfth (group B), eighteenth (group C) and twentyfourth (group D) weeks. Results: Group A did not develop tumor. Group B, C, D mice showed 71.4% 100% and 100% tumoral lesions, respectively. Eventually, it was found that 33% of the 36 lesions in the group of B, 50% of the 59 lesions in the group of C, 34% of the 67 lesions in the group of D were adenocarcinomas. When we have a looked at the distribution of the lesions in colon, we observed that dysplastic lesions and adenocarcinomas were mostly developed in the distal colon. Conclusion: As a result, after the repeated doses of DMH, we observed colonic tumors after a long period of latency in mice.