The pilot study will be carried out in two hospital catchment areas in South-East Norway - each with a target population of 70,000 men and women at 50-74 years of age - altogether 140,000 individuals to be randomised 1:1 between screening with an immunochemical test for faecal occult blood (iFOBT) biennially or FS once only. The primary endpoint is colorectal mortality reduction after 10 years. Attendance for FS is expected to be 50% and 60% for iFOBT. Expected CRC mortality reduction is 30% (286 CRC deaths) in the FS arm and 15% (143 CRC deaths) in the iFOBT arm (intention-to-treat). In a 1:1 randomisation with 80% statistical power and a significance level of 5% it will require 65,000 individuals in each arm to disclose a statistically significant difference between FS and iFOBT screening in an intention-to-treat model. We expect 5% in the iFOBTs group to test positive and require colonoscopy work-up. A positive FS is defined as 'any advanced neoplasia' (CRC, adenoma >10mm, adenoma with high-grade dysplasia or villous components). A finding of advanced neoplasia is expected in 5% of FS requiring full colonoscopy.