[Objective] To search a suitable preoperative intestinal cleansing method for the operation of colon and rectum. [Methods] A randomized controlled trial was applied in 70 cases before colic and rectal operations. Group A was give:n decoction of Folium Cassiae for oral use and saline enema and Group B was treated with saline enema only. The effect on intestinal cleansing was observed during the operation. [Results] In Group A, 26 cases were remarkably effective in intestinal cleansing, 8 effective, and 1 ineffective and 14, 16 and 5 in Group B respectively ( P