The diagnostic efficacy of magnetic resonance (MR) in the evaluation of cerebral venous angioma was studied. The results of MR and computed tomography (CT) were compared in six cerebral venous angiomas in five patients. MR alone was diagnostically successful in only three of six cases. Venous angiomas appeared as tubular structures of extremely low signal intensity on MR images. Although CT was highly sensitive (100%) in detecting lesions, CT was diagnostically specific in only four of the six cases. Angiography was the only modality able to unquestionably detect all six lesions. By varying the MR pulse sequence, we greatly affected the ability of MR to demonstrate lesions. In the cases where MR helped define the abnormality, T2-weighted MR images were able to clearly demonstrate lesions in five of the six cases whereas T1-weighted images helped detect an abnormality in only two cases. Although MR shows great promise in the evaluation of central nervous system abnormalities, CT remains the best imaging modality for detecting venous angiomas. When CT is not conclusive, angiography can be performed for a definitive diagnosis.