The diagnostic efficacy of routine double-contrast barium enema and fiberoptic coloscopy for detection of cancer was retrospectively studied in 303 patients consecutively operated for colorectal adenocarcinoma in a 52-month period from January 1980. Double-contrast barium enema was performed in 180 patients with 184 carcinomas, 157 (85%) of which were revealed by this examination. The detection rate of carcinoma according to site was 89% between cecum and descending colon, 92% in sigmoid colon and 71% in rectum. Fiberoptic colonoscopy was done in 176 patients with 181 carcinomas, 163 (90%) of which were detected by the endoscopical examination. The detection rate of carcinoma according to site was 86% between cecum and descending colon, 90% in sigmoid colon and 95% in rectum. The two methods were equally effective in detecting carcinoma of the colon. Colonoscopy was superior to barium enema in detection of rectal carcinoma.