Abstract: This study was to develop 5-aminosalicylic acid pellets preparation to achieve colon adhesive. 5-amino salicylic acid loaded pellet cores using Carbomer 940 and HPC as bioadhesive agents were prepared by extrusion spheronization. The maximum drug load, different forming agents and process parameters of the pellet cores were studied with the formability as an indicator. The bioadhesion effect of different proportions of two bioadhesive agents was investigated by in vitro adhesion experiments. The pellets core was coated with Surelease^® as inner layer for waterproof and Eudragit^® S100 as outer layer for pH control. The in vitro release of the 5-amino salicylic acid pellets was studied in media of different pH. The maximum drug load of the pellets was 70% and PH301 was the best forming agent. The weight ratio of Carbomer 940 to hydroxypropyl cellulose should be kept 1 ∶1 to achieve high bioadhesion. The amount of Surelease^® was 16% to 20% and Eudragit^® S100 was 28%. Dissolution profiles of coated pellets revealed no drug release in the artificial gastric fluid within 2 h and released less than 10% in pH 6. 0 phosphate buffer within 5 h, while the coated pellets dissolved quickly in pH 7. 4 colonic fluid with a good adhesion effect. This approach was successfully utilized in the preparation of 5-amino salicylic acid pellets with the good colonic adhesion.