Abstract: Background and aims: adenoma detection rate is a well known quality parameter for colonoscopy. However recently other quality parameters have emerged. We wanted to evaluate the histology of the resected polyps, different quality indicators of colonoscopy and post colonoscopy colorectal cancer (PCCRC) in Belgium and analyzed data about colonoscopies performed between 2008-2015.Methods: Reimbursement data on colorectal related medical procedures from the Intermutualistic Agency were linked with data on clinical and pathological staging of colorectal cancer and with histologic data of resected polyps available at the Belgian Cancer Registry over a period covering 8 years (2008-2015).Results: 298,246 polyps were resected in 294,923 colonoscopies, of which 275,182 were adenomas (92 %) and 13,616 were SSLs (4%). There was a significant but small correlation between the different quality parameters and PCCRC. Post colonoscopy colorectal cancer rate after 3 years was 7.29 %. There were marked geographic differences in Belgium concerning adenoma detection rate, sessile adenoma detection rate and post colonoscopy colorectal cancer.Conclusion: Most resected polyps were adenomas, only a small percentage involved sessile serrated lesions. There was a significant correlation between adenoma detection rate and other quality parameters, and a small but significant correlation between PCCRC and the different quality parameters. The lowest post colonoscopy colorectal cancer rate was reached with an ADR of 31.4 % and a SSL-DR of 1.2 %. (Acta gastroenterol. belg., 2023, 86, 277-285).