Acute colonic pseudo-obstruction which was first described by Sir Ogilvie in 1948 has been reported to be associated with various conditions but, its exact pathophysiology has not been defined. The most commonly associated condition is operation especially on pelvis or retroperitoneum. Malignancies with or without retroperitoneal invasion have been suggested to predispose to the development of Ogilvie's syndrome. Ogilvie's syndrome associated with gastric cancer has rarely been reported in the literature but, not in Korea. We report a case of Ogilvie's syndrome associated with gastric cancer in a 37-year-old woman. Its treatment was attempted by means of colonoscopic decompression and tube indwelling. Incomplete colonoscopic decompression was followed by cecostomy, but the patient died of sepsis on the 60th hospital day. (Kor J Gastroenterol 2000;36:99 - 104)