INTRODUCTION: Individuals with anxiety disorders often remain symptomatic despite treatment with a first-line pharmacologic agent. More research examining pharmacotherapy augmentation strategies to improve outcomes is needed. METHODS: In an 8-week, open-label, prospective augmentation study, we examined the efficacy and tolerability of the novel antipsychotic agent aripiprazole for adult outpatients with generalized anxiety disorder (n=13) or panic disorder (n=10) who remained symptomatic despite treatment for at least 8 weeks with an adequate (or maximally tolerated) dose of typical pharmacotherapy. RESULTS: Aripiprazole augmentation was associated with a significant reduction in Clinical Global Impressions-Severity scores (paired t=4.41, df=22, P<.001) in the intent-to-treat sample of 23 individuals. Three subjects (13%) discontinued due to sedation, chest discomfort, and restlessness, respectively. CONCLUSION: These data provide preliminary evidence that aripiprazole may be a useful augmentation strategy for individuals with generalized anxiety disorder or panic disorder who show a limited response to initial pharmacotherapy.