One of the most common cancers, colorectal cancer is a leading cause of cancer deaths worldwide. The vast majority of colorectal carcinomas develop slowly from easily-removed precursors (adenomas), and in contrast to most other types of cancer, chances of prevention and early detection are very good. Tests for fecal occult blood, sigmoidoscopy and colonoscopy are frequently recommended and widely used. Most western countries have initiated population-wide screening programs for colorectal cancer, with the goal of greatly reducing incidence and mortality. Various models for screening programs and different screening examinations have been proposed and implemented. Evidence from a range of countries shows that the highest participation rates are obtained when programs are designed to invite eligible individuals to come in for screening.