In a series of 60 intramedullary spinal cord tumors, there were eight cases of hemangioblastoma. Seven of these eight patients displayed evidence of diffuse spinal cord enlargement over multiple levels at a considerable range beyond the actual location of the tumor. One patient had a large intramedullary cyst that accounted for only part of the enlargement, and one had multiple tumor nodules. Six other patients had no obvious explanation for the diffuse cord enlargement. This phenomenon of extensive spinal cord enlargement appears to be unique to this type of tumor and not related to multiple tumors or extensive cyst formation. The cord enlargement seems to be related to edema and congestion of the spinal cord, perhaps secondary to the vascular shunt present in the hemangioblastomas. The possible pathophysiology and clinical importance of this observation is discussed.