Twenty-six patients (18 women and eight men) with giant cell tumors of the sacrum were treated from 1960 through 1986. The mean age of the patients was 29 years. The follow-up duration averaged 7.8 years. A neurologic deficit was present in 88%. Sixteen patients had not had a previous operation. Ten patients were referred for local recurrence. Twenty-one patients had radiation therapy; malignant transformation later occurred in three. Three benign giant cell tumors metastasized to the lungs. The local recurrence rate for patients treated by curettage was 33%. Three patients died of tumor-related complications. At the completion of this study, two patients were alive with disease. The suggested initial treatment is complete curettage. Radiation therapy should be reserved for incomplete resection and local recurrence. Occasionally, patients may require wide resection, which may cause a severe neurologic deficit and compromise spinal stability.