Background: The first, and possible most critical, step in colonoscopy is to have an adequately prepared colon. Unfortunately, none of the currently used colon cleansing regimens are completely satisfactory both in terms of patient complaints of unpleasant side effects and in terms of failure to provide a clean colon. The failure rate with traditional preparation is typically 10 to 30%. We used the Pulsed Irrigation Evacuation (PIE) device for colon cleansing. This device administers warm tap water through a cuffed speculum with microprocessor timed pulses of inflow and outflow. The rehydrated fecal matter is collected in a closed system which is discarded. The PIE technique is FDA approved for the management of fecal impaction. We hypothesized that use of PIE should result in rapid colon cleansing for colonoscopy with minimal patient discomfort. Methods: Consecutive outpatients scheduled for colonoscopy were offered the opportunity to participate. Main exclusion criteria were suspected bowel obstruction, previous colon resection, and severe congestive heart failure. Patients were advised to take clear liquids after 1 PM on the day prior to examination, one bottle of magnesium citrate (165 mL) the evening prior to examination and were kept NPO after midnight. Upon arrival to endoscopy suite, PIE was performed until the return was clear, followed by colonoscopy. Endoscopic photographs were taken in each segment of the colon, and video recordings were made. Patient discomfort during colon cleansing was assessed by a questionnaire. The quality of colon cleansing was graded using a previously used scoring system during the procedure. Two endoscopists also independently graded the quality of colon cleansing based on the photographs/video. Results: 20 consecutive patients participated (mean age = 60 yr - range of 45-80 yr). PIE was well tolerated. The only side effect was mild abdominal cramps during large pulses. Colonoscopy was complete to the cecum or terminal ileum in all. Colon cleansing was graded as acceptable or better in all (100% success: excellent = 4 patients, good = 15 patients, acceptable = 1 patient). The average time for cleansing was 25 minutes (range 20 to 35) and typically, approximately 6 gallons of water was required. Five patients had previous colonoscopy with GoLYTELY preparation and all preferred PIE. Conclusions: PIE results in optimal and rapid colon cleansing while causing minimal patient discomfort. It could be used as a primary colon preparation or for same day cleansing of those with poor traditional preparation.