Objectives The association of complications after renal surgery for renal cell carcinoma (RCC) with in-hospital mortality and costs remains to be defined. To describe the incidence of complications after open radical nephrectomy (ORN), laparoscopic RN (LRN), and open partial nephrectomy (OPN); and to evaluate its relationship with in-hospital mortality and total costs. Patients and Methods We identified 49 983 individuals who underwent ORN (35 712), LRN (5327), or OPN (8944) for RCC at 2037 hospitals from the Nationwide Inpatient Sample 2001-2008. The outcomes assessed were in-hospital mortality and total hospitalisation costs. Multivariable logistic regression and generalised estimating equations were used to test the associations between complications and in-hospital mortality and total costs. Results With 26.0% of patients experiencing postoperative complications, there were modest differences in the proportion of patients with complications after ORN, LRN, and OPN at 27.0%, 22.6%, and 24.0%, respectively (P < 0.001). After adjusting for patient and hospital variables, postoperative complications resulted in higher odds of in-hospital death for ORN (odds ratio [OR] 7.20; P < 0.001), LRN (OR 12.04; P < 0.001), and OPN (OR 7.82; P < 0.001). Adjusted total costs also rose significantly with the presence of any postoperative complications compared with those without any complications for ORN ($21 242 vs $13 183; P < 0.001), LRN ($19 548 vs $12 555; P < 0.001), and OPN ($18 883 vs $12 098; P < 0.001). Conclusions With about a quarter of patients experiencing postoperative complications, adverse events for ORN, LRN, and OPN carry a significant risk of in-hospital death and higher total costs. Efforts to reduce postoperative complications may correlate with substantial reductions in hospital mortality and total costs.