Seven hundred and twenty-three patients with colorectal carcinoma were treated consecutively from November 1973 to April 1997. Seven patients (0.96%) were found to have two colorectal carcinomas (synchronous carcinoma), located in separated colonic areas. Clinical histories were analyzed with reference to sex, age, symptoms, physical findings, disease localization, pathologic classification, and survival data. Preoperative diagnosis of synchronous lesions is difficult, being achieved in only 2 cases, but it is important for the proper treatment of patients. It is concluded that full examination of the colon in all patients presenting with primary colorectal cancer is mandatory and that colonoscopy should be used to effectively screen patients for synchronous cancers.