Pneumatosis cystoides intestinalis (PCI) is known to be a relatively rare condition which is characterized by gas cysts in the gastrointestinal mucosa. We treated four cases of PCI accompanied by hematological malignancies during chemotherapy treatment. All cases suffered from abdominal discomfort. Abdominal X-ray films revealed gas cysts in the intestine. PCI was observed during leukocytopenic states, and three cases had septicemia. Etoposide was administered to three cases, and prednisolone to all cases. It is considered that PCI sometimes occurs in patients with hematological malignancies during a period of leukocytopenia, and may be caused by intestinal mucosal damage due to myelosuppressive agents and immunosuppression from prednisolone.