Thirty-seven members of a family with von Hippel-Lindau disease (VHL) were prospectively screen for CNS hemangioblastomas; 10 family members were previously known to have VHL. Radiographic studies included noncontrast magnetic resonance (MR) imaging of the head (all patients) and spine (34 patients) and contrast-enhanced CT (CCT) of the head (all adult patients). Eleven patients had Gd-DTPA enhanced MR (CMR) of the head and 10 patients had CMR of the spine. Sixteen patients had radiographic evidence of CNS hemangioblastomas and all but six patients were symptomatic. Using comparable studies, CMR of the head demonstrated more lesions than the other modalities (31, 22, and 19 for CMR, MR, and CCT, respectively). Furthermore, CMR better separated tumor from edema, as well as cystic from solid components. Contrast enhanced MR was superior to noncontrast MR of the spine in lesion detection (31 vs. 4; p less than 0.001). Noncontrast MR was particularly limited in four patients with syringomyelia. We conclude that postcontrast MR of the head and spine is the best currently available means of detecting hemangioblastomas associated with VHL.