Colonoscopy examination is an important method to examine and establish the diagnosis of various diseases in the colon. Colonoscopy is successful when the tip of the scope reach the cecum and observe the caecal valve and/ or appendix orifice. This examination can be performed unsedated or under sedation (conscious sedation or deep sedation/general anaesthesia). The main disadvantage of unsedated colonoscopy method is the abdominal discomfort or pain during examination that may make patient distress and hemodynamically unstable and possibly stoppage of the examination before reach the cecum, but the severity of abdominal symptoms is vary from patient to patient. Many efforts have been tried to reduce the abdominal discomfort during examination. This unsedated method with air insufflation is our hospital standard method for colonoscopy examination since early 1980s, and less than 1% of patients were colonoscopied with conscious or deep sedation. Our study showed the success rate of this standard unsedated method was about 82%. The advantage of this method is inexpensive (feasible for most of people in developing country like us), patient may be examined ambulatory without escort, may back to work as soon as the examination is finished. Studies showed that replace the air insufflation with water infusion into colon since the beginning of the examination increased the success rate of caecal intubation and reduced the abdominal pain symptoms during colonoscopy examination(1). Sedation or general anaesthesia may increase the success rate of colonoscopy examination but it is costly, and may increase the adverse event especially in the elderly or patients with significance cardiopulmonary problems.