The purpose of this study was to assess the image quality and diagnostic value of MR urography in detecting abnormalities of the urinary collecting system relevant for the preoperative evaluation of living renal donors. Study subjects were selected from the existing intravenous urography (IVU) reports: 18 consecutive patients with a duplication or another abnormality of the collecting system and 20 consecutive patients with normal anatomy. They underwent a respiratory-triggered 3D T2-weighted fast spin-echo acquisition after oral administration of furosemide, without and with abdominal compression. The MR images were evaluated by two independent blinded observers. The IVU was used as the standard of reference. Image quality of the MR urograms with compression was overall better than those without compression, and the former were regarded as adequate for the evaluation of small filling defects and deformities of the pelvis and calyces in 76-81% of the kidneys and 74-79% of the patients. Both observers correctly diagnosed all 13 kidneys with a partial or complete duplication. The image quality of MR urography was inadequate to evaluate the calyces and pelvis for small filling defects or deformities in approximately 25% of the patients; however, the technique was accurate in the detection of abnormalities of the urinary collecting system relevant for the preoperative evaluation of living renal donors.