Abstract: The radionuclide trace technique is used to examine and determine that ~(99)Tc~m-5-aminosalicylic acid coated tablet delivere drug in colon. 5-aminosalicylic acid labelled with (~(99)Tc~m) is made to be coated tablet. Which character in artificial gastrointestinal liquid is observed by testing radioactivity leakage of the coated tablet, and in dogs vivo motor process by SPECT. Coated tablet is not dissolved in artificial gastric juice and outward appearance of which does not change.Coated tablet is take out after laid in artificial gastric juice for 1 h and placed in artificial intestinal liquid, partial coating is corroded and appears a great quantity of hole in a utensil at 3 h, and coating starts to burst and release at 3.5 h. The coated tablet starts to release drug in ascending colon and remain in colon for 6~7 h after taking orally. Therefore coated tablet of ~(99)Tc~m-5-aminosalicylic acid is able to release drug by location in colon.