Examination of lower part of digestive system by colonoscopy is necessity in occult fecal hemorrhage occurrence, hematochesis, unresolved loss of blood iron and suspicious finding of large bowel X-ray barium study. By therapeutical colonoscopy, haemorrhage from neoplasms and angiodysplastic changes are controlled, foreign bodies are removed as well as routine polipectomics. Balloon dilation of large bowel stenosis, and palliative treatment of unoperable stenoses lead to improvement in quality of life with significant cost-benefit effects. Follow-up of patients on high-risk for colorectal neoplasms increased early diagnosis of neoplasms.