We reviewed MR angiograms to evaluate its efficacy for visualizing the renal arteries and detecting renovascular disease. 41 renal arteries in 19 patients were examined by MR angiography. 3-D time-of-flight technique was used as routine examination method for MR angiography and 2-D time-of-flight technique was added in some particular cases to visualize venous flow. Within two weeks after MR angiography was performed, 23 renal arteries in 10 patients were additionally examined by conventional angiography or intraarterial DSA. The success rates of vessel visualization on MR angiography in normal renal arteries were 100% in main 67.7% in segmental, and 11.8% in intrarenal arteries. As a result of comparative study in normal main renal arteries with MR angiograms and conventional angiograms, overall correspondence in the number and the shape was noted and the caliber discrepancy between two examination did not exceed 3.0 mm. one arteriovenous fistula with aneurysm, one stenotic artery and two occluded arteries were well evaluated One arteriovenous fistula with aneurysm, and two occluded arteries were well evaluated by MR angiography. However three stenotic lesions were misdiagnosed as occlusions on MR angiography. and the overall accuracy was 87% We conclude that MR angiography has the potential to be a noninvasive and useful screening method for determining the number of renal arteries and for detection of abnormalities of main renal arteries.