Colorectal cancer is the second leading cancer sites in men (behind bronchial carcinoma) and women (after breast cancer) in Croatia, but also in Europe and the rest of the world. Conducting tests for occult blood in the stool and colonoscopy allows the diagnosis of colorectal cancer at an earlier stage, which increases the chances of survival and improves quality of life in patients with colorectal cancer. The risk of developing colorectal cancer increases after the age of 40, there with 90% of patients are over 50 years old. Given all of the above, according to the guidelines of the European Council in Croatia in 2007 began implementing The national program for early detection of colorectal cancer. The first cycle of the program was implemented from 2008 to 2010, while the second cycle of program implementation started in September 2013. The first cycle of program implementation showed that the response of the citizens participation in program was 21%, while 45% is satisfactory result, and the desired result id 65%. The aim of this paper is to determine what is the response of citizens from Zagrebacka County in participation in The national program for early detection of colorectal cancer and what are the reasons for non-response to citizens' participation in the program. The study included 52 subjects from Zagrebacka County who have not responded to colonoscopy. They were selected randomly and interviewed by phone. The results of the study show that response of citizens from Zagrebacka County in participation in the program is very low, so it is necessary to increase their response and extent of activities to implement the program, which relate to information, counseling and education of the total population, especially populations at increased risk of developing colorectal cancer (population older than 40 years), as people with lower educational status. In implementation of the program it is also necessary a better cooperation between all the participants and the involvement of family doctors and community nurses because they can most easily reach out to those people who should be invited to colonoscopy, especially those who have not responded to the survey in which the advisory measures of particular meanings.