The case histories of six infants and children (five male and two female) with hemangiopericytoma have been reviewed (two patients were born with the tumor). The tumor originated on an extremity in three patients, in the intranasal fossa in one, in the neck and upper mediastinum in one, and in the abdomen in another. In the patients with the tumor on the extremity, the lesion was removed with a margin of normal tissue. These patients remained well for 2,8, and 1.5 years after diagnosis. In the patient with an intranasal mass, the tumor was removed, but local recurrence developed 3 months later. The recurrent tumor was removed, and the patient remained well for 10 years. The patient with the neck and upper mediastinal tumor was born with the lesion and presented with airway obstruction at 2 months of age. This patient received radiotherapy and cyclophosphamide with no apparent response. He underwent partial excision of the lesion 1 month after diagnosis but died 1 month later from massive hemorrhage into the airway. The patient with the abdominal mass had extensive retroperitoneal tumor, and excision was not possible. He received chemotherapy and radiotherapy, and although the tumor decreased in size, osseous metastases developed 4 months after diagnosis. The metastatic lesions in this child disappeared with further chemotherapy, and at second-look operation 9 months after diagnosis, the tumor was removed. Postoperatively, new bone metastasis developed but again responded to chemotherapy with complete disappearance of the metastatic lesion. The patient had no evidence of disease 16 years after diagnosis.