Background and study aim: Colorectal cancer (CRC) screening is implemented by an increasing number of countries. Participation rates of screening programs influence the health benefit and cost - effectiveness of the applied method. The aim was to systematically review participation rate after first-time invitation for CRC screening with fecal occult blood test (FOBT), sigmoidoscopy, colonoscopy, and/or computed tomography (CT) colonography.Methods: A systematic literature search was performed prior to October 1 2009. Prospective CRC screening studies of unselected populations reporting participation rates were included. Results: After meta-analyses, overall participation rates were found to be 47 % for FOBT, 42 % for fecal immunologic tests (FITs), 35 % for sigmoidoscopy, 41 % for sigmoidoscopy combined with FIT/FOBT, 28 % for colonoscopy, and 22 % for CT colonography. Studies comparing screening methods showed higher participation rates for less invasive methods. Studies comparing invitation methods showed higher participation rates with general practitioner involvement, a more personalized recruitment approach, and reduction of barriers that discourage participation. Conclusions: Knowledge of identified factors affecting CRC screening participation can be used to improve screening programs.