In France, nearly 1.3 million colonoscopies are performed each year. Colonoscopy is the gold standard in France for colorectal cancer screening in populations at risk. However, it has a number of limitations. The quality of the bowel preparation is a critical step for the successful completion of this examination. The occurrence of interval cancers raises the problem of missed lesions. A literature review showed that there were differences between the endoscopy units on quality standards for bowel preparation. The rate of unprepared colonoscopy is estimated between 20 to 40% . In a recent cohort study, 28% of 2516 colonoscopies had a score of Boston of less than or equal to 6. These colonoscopies generate substantial additional costs to redo colonoscopies, estimated at 35 million euros in 2008. The establishment a predictive score for quality of bowel preparation based on a self-administered questionnaire completed by patients during the pre-colonoscopy consultation, would help identify patients at risk of poor preparation in order to optimize the prescribed preparation in this consultation.