Pneumatosis cystoides intestinalis (PCI) is a relatively rare, benign condition characterized by multiple subserosal or submucosal gas-filled cysts in the bowel wall . The cause and incidence of PCI are uncertain, but the condition is most commonly diagnosed in patients who have chronic obstructive pulmonary disease, gastrointestinal disease (e . g. Crohn's disease, peptic ulcer disease) or collagen disease (e . g. scleroderma, systemic lupus erythematosus). The report of PCI associated with nephrotic syndrome has not be known as far as we have referred. We first experienced a case of PCI with nephrotic syndrome . The patient was a 28-year-old female who had developed nephrotic syndrome in 1977. Although she had been treated by steroid since the onset of the nephrotic syndrome, she was a frequent relapser. She was hospitalized to our hospital on November 1988, due to fourth relapse of the disease. The increasing dosage of steroid (60mg/day) improved general edema and decreased urinary protein, but abdominal pain and fullness occurred seven weeks after the admission . The abdominal radiographs showed air accumulations in the wall of the intestine (probably right sided colon) and retroperitoneum . That finding was confirmed by Barium enema and abdominal computed tomography. We diagnosed the lesions as PCI from the above findings, and high flow oxygen and hyperbaric oxygen therapy improved the symptom of PCI. The etiology of PCI in this case was thought to be mainly a long term steroid treatment.