BACKGROUND: The benefits of adding upfront post-operative radiation, either whole-brain (WBRT) or cavity, after resection of brain metastases have been debated, particularly due to the long-term sequalae post radiation. We sought to compare the efficacy and safety between post-operative radiation versus resection alone. METHODS: We searched various biomedical databases from 1983 to 2018, for eligible randomized controlled trials (RCT). Outcomes studied were local recurrence (LR), overall survival (OS) and serious (Grade 3 + ) adverse events. We used the random effects model to pool outcomes. Methodological quality of each study was assessed using the Cochrane Risk of Bias tool. We employed the GRADE approach to assess the certainty of evidence. RESULTS: We included 5 RCTs comprising of 673 patients. The pooled odds ratio (OR) for LR is 0.26 (95% confidence interval (CI) 0.19-0.37, P < 0.001, GRADE certainty high), strongly supporting the use of post-operative radiation. Meta-regression analysis done comparing cavity and WBRT, did not show any difference in LR. The pooled hazard ratio (HR) for overall survival (OS) is 1.1 (95% CI 0.90-1.34, P = 0.37, GRADE certainty high). The treatment-related toxicities could not be pooled; the 2 studies which reported this did not find differences between the approaches. The risk of bias across the included studies was low. CONCLUSION: Our analysis confirms that upfront post-operative radiation significantly reduces the risk of LR. However, the lack of improvement in OS suggests that local control alone may not impact survival. Balancing local control, and neuro-cognitive effects of WBRT, cavity radiation seems to be a safe and effective option.