AIM: To relate the endoscopic findings in patients with hematochezia with regard to age in "low and average risk" for colorectal cancer (CRC) and to localize significant lesions in order to identify patients who need sigmoidoscopy or total colonoscopy.METHODS: This prospective study was performed in an open access GI endoscopy unit. Out of 4322 consecutive patients undergoing colonoscopy, 918 reported hematochezia. The final study group comprized 180 patients aged below 45 and 237 over 45. Main exclusion criteria were a 1st-degree family history of colorectal carcinoma,patients reporting blood mixed with stools and/or progressive colonic symptoms, or patients who had undergone colon surgery for neoplastic lesions.RESULTS: Total colonoscopy could be performed in 96% of patients. Abnormal findings were observed in 34.3% of the younger and in 65.7% of the older ones.Findings were the presence of polyps in the distal colon (n = 2) and IBD in the proximal colon (n = 29) in the group of the younger patients, and polyps (n = 15), IBD (n = 13), and carcinoma (n = 6, 4 of the lesions were located proximal to the splenic flexure) in the elderly.Our findings suggest that the diagnostic potential of total colonoscopy in patients younger than 45 referring scant hematochezia, is not mandatory. By exploring only the distal tract of the colon we have misdiagnosed two cases of IBD located in the ascending colon. In this group of patients additional risk factors must be identified before performing a total colonoscopy. Regarding the patients older than 45 yr, the exploration of the distal colon would have led to our overlooking a carcinoma, two neoplastic polyps and one IBD located in the proximal colon.CONCLUSION: Young patients with scant hematochezia but without risk factors for neoplasia do not need a total colonoscopy, whereas is mandatory performing a total colonoscopy in older patients even in the presence of anal pathology.