Objective: To identify preoperative clinical features that predict a durable improvement in renal function with renal artery stenting (RAS). Methods: Sixty-one patients with renal insufficiency (serum creatinine <1.5 mg/dL) underwent RAS for renal salvage. Patients were categorized as "responders" if estimated glomerular filtration rate (eGFR) at last follow-up was improved 20% or more over baseline. Patients with stable or worse renal function after RAS were labeled "non-responders." For the purpose of calculating changes in eGFR, patients on dialysis were represented by an eGFR of 10 ml/min/1.73 m2. Renal volume was estimated as kidney length × width × depth/2. Results: The median age of the cohort was 66 years (interquartile range [IQR], 60-73 years). Median preoperative serum creatinine was 1.8 mg/dL (IQR, 1.6-2.3), and median estimated glomerular filtration rate (eGFR) was 34 mL/min/1.73 m2 (IQR, 24-45). With stenting, 17 of 61 patients (27.9%) derived a durable improvement in renal function at a median follow-up of 24 months (IQR, 16-33 months). The largest proportion of stented patients (44.3%) had no improvement in renal function after stenting, while a subset (27.9%) experienced a decline in renal function. Responders enjoyed a 47% improvement in renal function from baseline, while non-responders had a 13% decrement in renal function (P < .0001). Responders had a higher baseline serum creatinine, lower eGFR, and a steeper decline in renal function prior to RAS, compared with non-responders. Kidney length, width, depth, and volume were not significantly different between responders and non-responders. Logistic regression analysis identified the rate of decline of renal function prior to stenting as the only independent preoperative predictor of improved renal function after RAS (odds ratio, 3.4; 95% confidence interval, 1.6 to 7.5; P = .0019). The rate of decline in eGFR per week was more than 20-fold greater for responders than non-responders (2.1% vs 0% decline in eGFR per week; P < .0001). No predictors of renal function deterioration after stenting were identified. Conclusions: The current study found that a steep decline in preoperative renal function portends a higher likelihood of renal salvage from RAS among patients with renal insufficiency. Incorporating this finding into patient selection may improve outcomes for RAS.