Colorectal cancer (CRC) is the second most common malignant disease in the European Union countries. It is a genetic disorder which is characterized by gradual accumulation of changes which lead to uncontrolled cell growth. Currently there are three paths of cancerogenesis known: chromosomal and microsatellite instability and CpG islands methylation. Majority of CRCs (80–85 %) are represented by the sporadic form with the age as the most important risk factor. Only 14–19 % of CRCs rise from inherited predisposition. Due to the relative long time of cancerogenesis, the detection of premalignant lesions by screening is crucial. The basic screening methods are fecal occult blood tests and colonoscopy. Colonoscopy examination is important in surveillance of CRC high risk patients and therapy (adenomatous polyps removal). The strict quality control recommended on diagnostic (adenoma detection rate, complete examinations) and therapeutic (prevention of complications such as perforation and bleeding) level is essential. It can be believed that due to the national CRC screening program (carried out since year 2000), the CRC mortality in the Czech Republic has been stabilized for long time. To its lowering, the highest participation of target population is necessary. It can be achieved by intensive participation of medical specialists and the executive.