A retrospective study has indicated that stereotactic radiotherapy (SRT) has a value in treating both primary tumors and singular metastatic lesions that cause local symptoms. Here we present the results of a prospective study evaluating the safety and local efficacy of SRT in metastatic or inoperable primary renal cancer. Thirty patients with metastatic renal cell carcinoma (RCC) or inoperable primary RCC received high-dose fraction SRT. In total, 82 lesions were treated. Dose/fractionation schedules varied depending on target location and size. The most frequently used fractionations were 8 Gy x 4, 10 Gy x 4, 15 Gy x 2 or 15 Gy x 3 prescribed to the periphery of the PTV. Local control, defined as radiologically stable disease (SD) or partial/complete response (PR/CR) was obtained in 98% of treated lesions but 19% of lesions were in patients with a follow time of less than 6 months. CR was observed in 21% of the patients and 58% of the patients had a partial volume reduction or local stable disease after a median follow-up of 52 months (range 11-66) for patients alive and 18 months (range 4-57) for deceased patients. Local progression was seen in two lesions. Side effects were grade I-II in 90% of cases. The overall survival was 32 months. SRT for patients with primary and metastatic RCC resulted in high local control rate with generally low toxicity. The method can thus be considered a therapeutic option to surgery in patients with a limited number of metastases, as local treatment in RCC with an indolent presentation or as a method of reducing tumor burden prior to medical treatment.