To evaluate the efficacy of adjunctive aripiprazole in patients with minimal response to prior antidepressant therapy (ADT). Pooled data from three randomized, double-blind, placebo-controlled studies assessing the efficacy of adjunctive aripiprazole to ADT in patients with major depressive disorder who had a minimal response [< 25% reduction on the Montgomery-Åsberg Depression Rating Scale (MADRS)] to an 8-week prospective ADT. During the 6-week, double-blind adjunctive phase, response was defined as at least 50% reduction in the MADRS score and remission as at least 50% reduction in MADRS score and a MADRS score ≤ 10. Rates were examined using analysis of covariance and Cochran-Mantel-Haenszel tests. Kaplan-Meier curves were used to calculate time to response and remission. Of 1038 patients, 72% (n=746) exhibited a minimal response to ADT (ADT minimal responder). Time to response and remission were significantly shorter for ADT minimal responders receiving aripiprazole+ADT versus adjunctive placebo+ADT. ADT minimal responders on aripiprazole+ADT showed significantly greater improvements in MADRS score at endpoint compared with minimal responders on placebo+ADT (-10.3 vs. -6.5, P<0.0001). In addition, ADT minimal responders exhibited significantly higher response rates with aripiprazole+ADT than placebo+ADT (36 vs. 19%, respectively, P<0.0001) and higher remission rates (24 vs. 12%, respectively, P<0.0001). The numbers needed to treat with aripiprazole+ADT were six for response and eight for remission. Aripiprazole augmentation had a rapid and clinically meaningful effect in ADT minimal responders.