The each rumen of six goats was incised and sutured with chromic catgut, polyglycolic acid and nylon. Tissue reaction to each suture materials was observed and comared at the 7th, 14th and 21st post-operative days. The predominent inflammatory cells around suture materials are macrophages, fibroblast and neutrophils. A few lymphocytes was infiltrated around suture materials. Infiltration of neutrophils was rapidly diminished but infiltration of macrophages, fibroblasts and lymphocytes were persisted. The overall grade of tissue reaction varid by suture materials. At the 7th post-operative days, tissue reaction to chromic catgut was most prominant and that of polyglycolic acid and nylon was moderate. At the 14th and 21st postoperative days, tissue reaction to each suture materials was not greatly different.