OBJECTIVE To determine whether presurgical sunitinib reduces primary renal cell carcinoma (RCC) size and facilitates partial nephrectomy (PN). METHODS Data from potential candidates for PN treated with sunitinib with primary RCC in situ were reviewed retrospectively. Primary outcome was reduction in tumor bidirectional area. RESULTS Included were 72 potential candidates for PN who received sunitinib before definitive renal surgery on 78 kidneys. Median primary tumor size was 7.2 cm (interquartile range [IQR]: 5.3-8.7 cm) before and 5.3 cm (IQR: 4.1-7.5 cm) after sunitinib treatment (P<0.0001), resulting in 32% reduction in tumor bidirectional area (IQR: 14%-46%). Downsizing occurred in 65 tumors (83%), with 15 partial responses (19%). Tumor complexity per R.E.N.A.L. score was reduced in 59%, with median posttreatment score of 9 (IQR: 8-10). Predictors of lesser tumor downsizing included clinical evidence of lymph node metastases (P<0.0001), non-clear cell histology (P = 0.0017), and higher nuclear grade (P = 0.023). Surgery was performed for 68 tumors (87%) and was not delayed in any patient owing to sunitinib toxicity. Grade ≥ 3 surgical complications occurred in 5 patients (7%). PN was performed for 49 kidneys (63%) after sunitinib, including 76% of patients without and 41% with metastatic disease (P = 0.0026). PN was completed in 100%, 86%, 65%, and 60% of localized cT1a, cT1b, cT2, and cT3 tumors, respectively. CONCLUSION Presurgical sunitinib leads to modest tumor reduction in most primary RCC, and many patients can be subsequently treated with PN with acceptable morbidity and preserved renal function. A randomized trial is required to definitively determine whether presurgical therapy enhances feasibility of PN.