We present a retrospective study on 610 patients with colorectal cancer diagnosed over a 10 year period; 21 patients (3.4%) had synchronous multiple primary carcinomas. Age and clinical symptoms were similar to those with single carcinomas. In 57% of patients, the presence of synchronous neoplasms was diagnosed preoperatively by colonoscopy and/or barium enema, in 38% peroperatively and in 5% postoperatively. The more frequent localizations were rectum-sigmoid colon (24%) and descendent colon-sigmoid colon (19%). Three patients had 3 synchronous tumors, respectively. According to the Dukes classification, 80% of the patients had stage B or C. The five-year survival rate was 61%, similar to that for colon cancer in general. We emphasize the importance of preoperative identification of synchronous lesions; the whole colon should be investigated before surgery in order to ensure that no synchronous tumor has been missed or to change planned surgery.