OBJECTIVES: Through the earlier detection and removal of cancerous and precancerous adenomas, colorectal cancer (CRC) screening aims to reduce both the risk to individuals and burden on healthcare systems. Inadequate bowel preparation prior to colonoscopy correlates with a higher rate of missed adenomas, especially in the right colon. The differential cost and efficacy of available bowel cleansing products mean that healthcare providers are faced with a decision that has both economic and public health consequences. A model was therefore constructed to investigate the long term benefits of adequate bowel cleansing. METHODS: The cost-consequence model compares the total cost of colonoscopy, and treatment of subsequent CRC, over a 10 year time horizon in a cohort of 10,000 patients aged ≥55 years receiving either 4L of polyethylene glycol (4LPEG), 2L of PEG with ascorbate (2LPEG+ASC), or 1L of sodium picosulphate with magnesium citrate (NaPic/MgCit) prior to colonoscopy. Rates of successful bowel cleansing, completed colonoscopies, and adenoma detection rate (ADR) were obtained from clinical trial data, together with published rates of surveillance colonoscopy, associated costs, and healthcare resource utilisation in Germany. RESULTS: In the model, poor compliance with the higher volume 4LPEG leads to a lower rate of completed colonoscopies, and more missed adenomas than with lower volume 2LPEG+ASC. Moreover, the superior compliance and higher ADR achieved using 2LPEG+ASC, particularly in the right colon, results in more cases of CRC prevented over 10 years than 4LPEG and NaPic/MgCit (25 and 113 more cases, respectively). Through a decrease in treatment of CRC, this equates to an average overall cost saving of €213 and €625 per patient, respectively, over 10 years. CONCLUSIONS: Optimisation of bowel cleansing prior to colonoscopy is likely to increase the detection (and removal) of cancerous and precancerous adenomas, which may reduce the development of CRC, avoid treatment costs, and reduce mortality.