 This is a once-only screening concept with bowel cleansing being limited to a 240 ml Sorbitol enema given on attendance. The threshold for work-up colonoscopy is low as a positive screening test is defined as any polyp 9mm, any histologically verified adenoma irrespective of size and a positive FOBT. The screening phase is limited to the period January 1999- January 2002 and the first follow-up results will not be reported until all entries have passed the 5-year mark i.e. in early 2007. 