Intussusception occurred in eight children during treatment of malignancy with irradiation, chemotherapy, and operation, or a combination thereof. Metastatic tumor masses served as "leading points" for the intussusception in only two patients. The insidious onset of symptoms led to a diagnostic delay of 5 to 30 days before operation or death. The intussusception was localized to the small bowel in seven patients. Early operative intervention is recommended.