The efficacy and safety of the new colonic lavage solution, Golytely (an electrolyte-polyethylene glycol solution), was compared with standard 2- and 3-day bowel preparations in a randomized blinded study of patients undergoing colonoscopy and barium enema examination. Side effects, patient preference, and quality of examinations were monitored. Colonoscopy was scored by colonic segment for type of residual stool and percentage of bowel wall visualized. Barium enema was graded by stool particle size in the least clean segment. For colonoscopy, preparation with Golytely allowed better visualization of colonic mucosa (p less than 0.002) due to less retained stool (p less than 0.002), produced more optimal exams (p less than 0.002), and required less time to reach the cecum (p less than 0.05). Furthermore, it was preferred by patients, required less than 5 preparation time, and caused no notable side effects. For barium enema, no significant difference existed between preparations. We conclude that Golytely is effective for barium enema examination and is the preparation of choice for colonoscopy.