In minimally sedated Asian patients in a community setting the investigators showed that a limited volume of water infusion instead of air insufflation in either the rectal sigmoid colon or the whole colon significantly reduced pain score during colonoscopy. Cecal intubation rate was not compromised. The reduction of pain score ranges from 25% to 32 % in our previous studies.1, 2 In contrast, several US reports described the successful use larger volumes of water infused throughout the entire colon in patients undergoing colonoscopy which result in a greater reduction of the pain score, averaging about 56%.3-5 A recent review suggested that the cause of the difference might lies in the timing of water removal.6 Specifically, the investigators group removed the infused water predominantly during withdrawal phase (water immersion) and the U.S. group removed water during insertion phase (water exchange).