Pneumatosis cystoides intestinalis is a relatively rare condition, characterized by multiple gas-filled cysts of varying size in the wall of gastrointestinal tract. Although the etiology of pneumatosis intestinalis remains uncertain, the possibility that both the gas-forming bacteia and mechanical theories develop pneumocysts has recently been advocated. We experienced a case of pneumotosis cystoides in testinalis found by colonoscopy in a 31-year old woman with intermittent abdominal pain. (Korean J Gastrointest Endosc 2001;23:251-254)