The cleansing effect of whole-gut irrigation with a balanced electrolyte solution (BES), with or without pretreatment with bisacodyl, was compared, in order to establish whether bisacodyl reduces the duration and side effects of whole-gut irrigation. Bisacodyl at a dose of 20 mg in 2 days reduced the duration of the whole-gut irrigation procedure. No side-effects related to bisacodyl were demonstrated. We therefore consider bisacodyl to be a useful and inexpensive adjunt for colonic preparation of patients receiving whole-gut irrigation.