Background: Metastatic renal cell carcinoma (mRCC) management guidelines recommend brain imaging if clinically indicated and the rate of occult central nervous system (CNS) metastasis is not well-defined. Early detection could have major therapeutic implications, because timely interventions may limit morbidity and mortality. Patients and Methods: A retrospective review was performed to characterize patients with mRCC incidentally diagnosed with asymptomatic brain metastases during screening for clinical trial participation at Gustave Roussy and Memorial Sloan Kettering Cancer Center. Descriptive statistics and time-to-event methods were used to evaluate the cohort. Results: Across 68 clinical trials conducted between 2001 and 2019 with a median 14.1-month follow-up, 72 of 1,689 patients (4.3%) with mRCC harbored occult brain metastases. The International Metastatic RCC Database Consortium (IMDC) risk status was favorable (26%), intermediate (61%), and poor (13%), and 86% of patients had ≥2 extracranial sites of disease, including lung metastases in 92% of patients. CNS involvement was multifocal in 38.5% of patients, and the largest brain metastasis was >1 cm in diameter in 40% of the cohort. Localized brain-directed therapy was pursued in 93% of patients, predominantly radiotherapy. Median overall survival was 10.3 months (range, 7.0–17.9 months), and the 1-year overall survival probability was 48% (95% CI, 37%–62%). IMDC risk and number or size of lesions did not correlate with survival (log-rank, P=.3, P=.25, and P=.067, respectively). Conclusions: This large multi-institutional mRCC cohort study identified occult brain metastasis in a notable proportion of patients (4.3%) and highlights that the risk of asymptomatic CNS involvement extends to those with favorable risk features per IMDC risk assessment. These data provide rationale for brain screening in patients with advanced RCC.