OBJECTIVE Local tumor ablation (LTA) and partial nephrectomy (PN) represent treatment alternatives for patients diagnosed with small renal mass and both may result in renal function detriments. The aim of the study was to compare renal function detriments after LTA or PN. METHODS A Surveillance epidemiology and End Results-Medicare-linked retrospective cohort of 2850 T1 kidney cancer patients who underwent LTA or PN was abstracted. Short-term outcomes consisted of 30-day acute kidney injury (AKI) and 30-day dialysis rates. Long-term outcomes consisted of episodes of AKI, mild and moderate-severe chronic kidney disease (CKD), end-stage renal disease, hemodialysis and anemia in CKD. Analyses consisted of propensity score matching, logistic and Cox regression. RESULTS After propensity score matching, 1122 patients remained. The 30-day incidence of AKI was 4.6 % after LTA and 9.4 % after PN. In multivariable analyses (MVAs), LTA was associated with a lower AKI rate (OR 0.42; p = 0.001). The 30-day incidence of any dialysis was <2 % after either LTA or PN. In MVA, LTA was not associated with a lower rate of any dialysis (OR 0.43; p = 0.2). At long-term assessment, both the unadjusted and adjusted rates of all six examined end points were not different between LTA and PN (all p > 0.5). CONCLUSIONS LTA offers short-term protective effect from AKI. The short-term rates of any dialysis treatment are similar after either LTA or PN. At long-term assessment, LTA and PN renal function detriment rates are not different. Concern for long-term functional outcomes should not be a barrier for PN.