In colorectal carcinomas, thara may be one or more neoplasm in colon. That may be synchronous or metachroonous. Tumors that occur at one or more focus at the same time are called synchronous. But, if they are diagnosed in different timee, called metachronous.Both synchronous and metachronous tumors are usually observed aat different side of colon and, allm›st aallways adenocarcinomas histologically. It’s important that preoperative colonoscopy is necessary to detect synchronous tumor for all cases with colon carcinoma. If colonoscopy could not performed, radiographic examinations must be used. Especially, synchronous tumor that’s small and not inflitrate the serosa of colon is difficult to diagnose and may be out sight.In these case; a patient have only a rectosigmoid colon carcinoma that indicated by colonoscopy and coputerized tomography was operated in which another tumor rin caecum was observed and subtotal colectomy was performed. Both of biopsy materials shown adenocarcinoma histopatoologically. In operation for carcinoma of colon,synchronous tumor may keeped in mind and it must remembered that it may occur at different localization of colon. Abdominal explorations is important for especially young colon carcinoma sufferers. Finally, preoperative colonoscopy seems to be important examination for synchronous tumor.

Keywords: Colon carcinoma, Synchronous tumor