PURPOSE: To evaluate the usefulness of MR urography(MRU) using Half-Fourier acquisition single-shot turbospin-echo(HASTE) sequence compared with conventional intravenous urography(IVU). MATERIALS AND METHODS: Thirtyfive lesions of 32 patients who underwent MRU because of delayed excretion or nonvisualization of the ureter wereincluded in this study. HASTE MR urography was performed with a 1.0 MR imaging unit. Coronal images includingthose of the kidney, ureter and bladder were obtained in every patient using the multislice technique, and werepostprocessed by means of the maximal intensity projection technique. Scan time was 17-19 seconds. We analyzed theresults of MRU, focusing on level of obstruction, incidence of stone, ureter dilatation, and motion artifact, andin each case compared MRU findings with those of IVU. RESULTS: In 12 of 35 lesions(34.2%), MRU more effectivelydiagnosed causes of obstruction than did IVU, while in seven lesions(20%), MRU and IVU were similar. In eightlesions(22.9%), all of which were caused by a stone, IVU was better than MRU, and in a further eight, neithermodality was able to diagnose the cause. For diagnosis of the level of obstruction, MRU was better than IVU in 20of 35 lesions(57.1%), and similar to IVU in seven(20%). In three lesions(8.6%), neither modality was able todetect the level of obstruction. Four lesions not related to obstruction were polycystic renal disease, cysticrenal change, vesicovaginal fistula and extra-renal pelvis. Dilatation of the ureter was seen in 23lesions(65.8%) on MRU and in seven lesions on IVU. Thus, MRU revealed dilatation of for the ureter more efectivelythan IVU. CONCLUSION: MRU using HASTE was valuable for the detection of underlying causes and levels ofobstruction in the urinary tract, and of abnormalities in surrounding structures in patients with non-visualization of the kidney or delayed contrast excretion of the ureter, as seen on delayed IVU urogram.