Up to 360 hospital in-patients routinely scheduled to undergo complete colonoscopy were to be enrolled one to two days prior to the endoscopic procedure, and to be randomly allocated to one of the two treatment arms in a ratio of 1:1. Bowel preparation was performed using equal split doses of either low-volume NRL994 (two doses of 1,000 mL each) or high-volume PEG+E (two doses of 2,000 mL each). The first dose was to be taken in the evening before the procedure, the second dose on the morning of the day of the colonoscopy. The patients allocated to NRL994 were asked to drink at least 1L of additional clear liquid in addition to the study drug. During colonoscopy the cleansing of each of the five pre-defined gut segments was to be assessed by the physician performing the examination, using a 5-level verbal rating scale. Videotapes were to be recorded of all procedures in order to allow central review by a blinded and independent expert panel whose ratings were the primary basis for the analysis of efficacy. The patients enrolled in the study were asked to fill in a questionnaire concerning the acceptability of the preparation. A patient's participation in the study was terminated upon completion of the intervention by performing a final examination and filling in the study termination page. No interim analysis was to be performed.