['At least 6-10 min of withdrawal time is currently recommended to optimize polyp yield in screening colonoscopies in individual with intact colon. We aimed to assess whether formal documentation of withdrawal time could improve the quality of colonoscopy observation.', 'During December 2006, we implemented withdrawal time as a mandatory field for formal colonoscopy report. Colonoscopy withdrawal time and adenoma detection rate was compared between periods before (Nov 2006) and after (Jan 2007) formal documentation. A total of 709 colonoscopic procedures, which were performed by 9 colonoscopists in training (fellows) were analyzed.', "The median withdrawal time of 'negative colonoscopy' increased from 6m06s to 6m36s (p=0.045). The number of adenoma detected in each colonoscopy between the two periods was 0.66 and 0.81 (p=0.813). Two out of 9 colonoscopists increased withdrawal time significantly (6 m 11 s to 7 m 52 s, p=0.001) after formal documentation of withdrawal time and demonstrated higher detection rate for adenoma smaller than 10 mm (0.34 per colonoscopy vs. 0.83 per colonoscopy; p=0.012)."] Does formal documentation of withdrawal time improve the quality of colonoscopic observation?