Magnetic resonance imaging (MRI) of bladder carcinoma was performed in 10 patients who subsequently underwent operations for tumor staging. MRI was performed with a 0.1 T resistive magnetic resonance unit. Images were obtained in the transverse, coronal and sagittal directions with different repetition and echo times. Simultaneously, computed tomography (CT) was performed in 9 of the 10 patients. The accuracy of MRI and CT staging was then evaluated by comparison with the staging from pathologic diagnosis. All of the tumors, which were 2.3-6.3 cm in diameter, were readily depicted by both imaging techniques. The overall accuracy of MRI staging for the 10 patients in whom staging had been pathologically confirmed was 90%, while the accuracy of CT staging for the 9 patients was 55%. Although no statistically significant differences in accuracy between CT and MRI staging can be established on the basis of the above results because of the small number of patients included in this study, MRI appears to be a very useful modality for staging bladder carcinoma.