The Spanish Cancer Screening Network involves the participation of all regional programmes and has been working for over 20 years to co-ordinate strategies and implement quality assurance in current and new regional programmes. In colorectal cancer, the target population is the group aged 50-69 years, who are offered biennial testing using the faecal occult blood test in all programmes, with follow-up colonoscopy if the faecal occult blood test is positive. This article presents the main trends, indicators and differences by sex. The main indicators from 2006 to 2011 were analysed: coverage, participation rate, positivity rate, colonoscopy uptake and lesions detected. Annual trends were adjusted by sex and region. In 2011, coverage was 9.74% of the Spanish target population. A total of 1 001 669 first invitations were registered from 2006 to 2011 and 596 649 individuals participated in the programmes (43.83% participation rate). Results were positive in 30 544 individuals (5.47%), with the lowest positivity rate occurring in 2007 (3.06%) and the highest in 2011 (6.30%) (P<0.001). In all, 27 568 colonoscopies were registered, with a high compliance rate (90.00% in 2011 and 95.59% in 2007) (P=0.381). The adenoma and colorectal cancer detection rates increased over the period, reaching 32.25/1000 and 3.42/1000 participants in 2011, respectively (P<0.001 and P=0.001). Comparison of differences by sex showed that detection rates were significantly higher in men than in women (P<0.001). Participation increased over time and has now reached an acceptable rate. Men show low participation but higher detection rates, indicating the need for further intervention. The Spanish Cancer Screening Network provides common evaluation, performance and organizational benchmarking.