We report a clinic-endoscopical study about 365 patients, both of sex, between 26-95 years old, with colonoscopic diagnosis of colorectal cancer. Results showed that 61,92% were men and 38,08% women; in 92,60% the disease ocurred over 40 years old. 13,42% had malignant personal history -colorectal cancer, uterus and breast cancer, and others-; 13,97% had bening personal history-colorectal adenoma, cholecystectomy, and others-; Abdomina pain, change in intestinal habits, and bleeding were the moist frequent symptoms, with differences depending of the tumors localization in the colon or rectum. 62,57% of patients had anemia under 10g% of hernoglobin; in 85,23% the fecal occult blood test was positive. On 199 patients, the simple barium enema diagnosed the tumor in 66,33% only; but in the same group, colonoscopy diagnosed the cancer in 96,49% at first examination. In all patients, colonoscopywas excellent for diagnosis of the principal lesion, and for the identification of synchronous neoplasia. On 365 patients, colonoscopy diagnosed the cancer in 98,08% at first examination. The localization of tumors was: 57,63% in left colon (49,47% in rectum and sigmoid colon); 34,21% in the right colon; and 8,16% in transverse. Pathology showed that adenocarcinoma was the most frequent tumor 95,23%; 1,06% mucoid carcinoma; 1,06% epidermoid carcinoma; and 2,65% lymphorna. In 32,05% of cases there were synchronous lesions; 3,01% had other cancer, and 54 patients had 112 polyps (62,50% adenomatous polyp, 6,25% adenoma with non invasive or invasive adenocarcinoma, and 31,25% hiperplastic polyp.Authors emphasize the value of the detection and early diagnosis to decrese the colorectal cancer mortality.