56 patients with bladder carcinoma were examined by magnetic resonance in the pre-operative staging. In 40 patients where total cystectomy with enterocystoplasty and pelvic node dissection were performed, a good correlation with surgical and pathologic findings was obtained. MR examination using T1 (TR 400 ms, TE 28 ms) and T2 (TR 1,200-1,600 ms, TE 40 80 120 ms) weighted images in different planes where performed after biopsy of the bladder tumor through endoscopy and within 1 or 2 weeks before surgery. Neoplasms were characterized by site, size and growth pattern. Extension through the deep muscle of the bladder wall was correctly identified in 95% with a sensitivity of 95% and a specificity of 95%. Extension through perivesical fat was assessed accurately in 85% with a sensitivity of 66% and a specificity of 100%. Accuracy in evaluating invasion of adjacent organs was 85%, sensitivity 44%, specificity 96%. Lymphadenopathy has been accurately assessed in 97.5% with a sensitivity of 83% and a specificity of 100%. MR correctly staged the tumor according to TNM classification in 24/40 (60%) patients, overestimated the extension in 3/40 (7.5%) and underestimated the extension in 13/40 (32.5%).