Background: Immuno-oncology (IO) checkpoint inhibitors have demonstrated efficacy in metastatic renal cell cancer (mRCC) treatment. Real world data is required to assess outcomes when applied to the general population. Methods: A retrospective analysis was performed using the IMDC database. It included mRCC patients treated with IO agents, including atezolizumab (Atezo), avelumab, ipilimumab, nivolumab (Nivo), and pembrolizumab (Pembro). Some patients were treated with combination therapy with a targeted agent. Patients may have received IO therapy as first-, second-, third-, or fourth-line treatment. Overall survival (OS), treatment duration, and overall response rates (ORR) were calculated. Results: 255 patients with mRCC treated with IO therapy were included. The ORR to IO therapy in those patients who were evaluable was 29% (32% first-, 22% second-, 33% third-, and 32% fourth-line therapy). Patients treated with second-line IO therapy were divided into favorable, intermediate, and poor risk using IMDC criteria; the corresponding median OS rates were not reached, 26.7 mo, and 12.1 mo, respectively (p<0.0001). Conclusions: Response rates to IO therapies appear to remain consistent no matter which line of therapy it is used in. Within second-line treatment, IMDC criteria appear to stratify patients appropriately into favorable, intermediate, and poor risk groups. Survival data are premature and will be updated. In contrast to Nivo clinical trial data, where median treatment duration was 5.5 mo, longer treatment length is observed in real world practice.