The purgative effect of bisacodyl, anthraquinone glycosides (Cascara), and sodium picosulfate, alone or in combination with a saline purge and a tap water enema, was studied in 1200 patients. The cleansing effect was scored with regard to retained fecal residue evident on double-contrast studies of the colon. The combination of a contact laxative and a saline purge produced good cleansing effect in 52%-80% of the patients. With an additional tap water enema given 1 hour before the colon examination, however, 96% of the colons were clean. The taste and the effects of the cleansing systems were tolerated favorably by more than 90% of the patients. However, 17% reported restriction in work capacity on the day of bowel cleansing.