Giant cell tumors of synovium (pigmented villonodular synovitis) involving the vertebral column recently have been seen in two women: the third and fourth cases to be reported in the English-language literature. Unlike the previously reported cases, both these tumors grew outside the dura and produced symptoms of spinal cord compression. The first case involved lumbar vertebrae 5 and 6; the second, lumbar vertebrae 2 and 3. Even though initial resection of both tumors was incomplete, the patients improved postoperatively. One tumor was known to be unresectable at the time of surgery. In the other patient, a recurrence of symptoms required second and third resections 4 and 8 months after the first, respectively. Although synovial giant cell tumors rarely metastasize, the rate of local recurrence is high, especially if excision is incomplete. For this reason, close follow-up of patients with lesions in the spinal column is indicated. Increased physician awareness that synovial giant cell tumors can occur in the spine will help to ensure that these tumors are not misdiagnosed in this location.