There is currently limited data on which drug should be used to improve blood pressure (BP) control in patients with resistant hypertension (RH). We performed a systematic review and meta-analysis of published studies evaluating the anti-hypertensive benefit of aldosterone antagonists (AA) as an add-on therapy in patients with RH. A systematic literature search for eligible studies was conducted until June 2014, using literature databases and hand search. Studies were stratified according to controlled vs uncontrolled design and analyzed using random-effect models. We identified 13 eligible studies involving a total of 2640 patients, consisting of 3 randomized controlled trials, and 10 observational studies without a control group. In controlled studies, there was a reduction in mean systolic and diastolic BP of -16.5 (95% confidence interval (CI), -30.0 to -3.0) and -4.1 (95% CI, -7.8 to -0.32) mm Hg, respectively, compared with control. In uncontrolled studies, there was a reduction in mean systolic and diastolic BP of -19.7 (95% CI, -23.2 to -16.2) and -9.1 (95% CI, -10.3 to -7.8) mm Hg, respectively, compared with pre-AA therapy. Subgroup analysis showed that the systolic BP change was more pronounced in patients with baseline systolic BP >150 mm Hg (weighted mean difference (WMD), -23.1 mm Hg) than in patients with ⩽150 mm Hg (WMD, -15.4 mm Hg) (between groups P<0.001), suggesting that the baseline systolic BP was a predictor of the BP response to AA treatment. Furthermore, AA demonstrated a mild increase in serum potassium and creatinine (for both, P<0.001). The findings suggest that AA as an add-on therapy was effective for lowering systolic and diastolic BP in patients with RH.