Renal artery stenting is expected to improve or stabilize renal function. However, the efficacy of renal artery stenting in severely reduced renal function is unclear. We evaluated 23 patients with class IV or V renal dysfunction who were treated for renal artery stenosis between 2004 and 2009. Improvement in renal function was found in 7 (30%) patients, all of whom were treated with distal protection device. Deterioration of renal function was found in 4 (17%) cases. In these 4 cases, distal protection device could not be used for anatomical reasons. The use of distal protection device was associated with significantly less renal deterioration after the procedure (P < .05, odds ratio 0.21 [confidence interval 0.09-0.50]). Renal artery stenting can stabilize or improve renal function in patients with severe renal dysfunction. Distal protection devices may be beneficial in patients who require renal artery stenting due to severely reduced renal function.