The objective of our study was to assess the real-world safety and efficacy of nivolumab in the second- or later-line treatment of metastatic renal cell carcinoma (mRCC). We conducted a multicenter, retrospective, observational study of real-world data from patients who were treated with nivolumab under a patient expanded access program from 2015 to 2017 in Croatia, Hungary, and Malta. The primary safety endpoint was the discontinuation of therapy because of adverse events. The primary efficacy endpoint was overall survival (OS). We collected data from 87 patients with a median (interquartile range (IQR)) age of 63 (57-68) years, and 21% were females. The median (IQR) follow-up was 11 (5-31) months. Treatment was discontinued because of toxicity in 4 (5%) patients. Four (5%) patients experienced treatment-related adverse events of grade 3 or 4. The OS was 18.0 (95% CI: 11.0 to 28.6) months, and the PFS was 8.5 (95% CI: 4.9 to 12.1) months. Our study indicated a good safety and efficacy profile of nivolumab in the second- or later-line treatment of mRCC patients in a real-world clinical practice environment, which is comparable with the findings of the registrational trial.