A partial obstruction of small intestine was diagnosed by physical and radiographic examination in a dog which had signs of anorexia, vomiting, diarrhea and dehydration The dog was treated by surgical method. String-like foreign body was located from stomach to upper jejunum. Diffuse laceration, inflammation and perforation caused by foreign body were observed in intestine. Intestinal resection was carried out to remove the foreign body from upper duodenum to upper jejunum. The dog was convalesced successfully after operation.