In order to examine the benefit of adding pharmacotherapy to cognitive-behavioral therapy (CBT) for anxiety disorders, we searched for studies comparing CBT plus pharmacotherapy and CBT plus pill placebo for adults meeting DSM-III-R or DSM-IV diagnostic criteria for an anxiety disorder between the 1st available year and July 1, 2008. Of 874 studies that were initially considered, 11 studies were identified, representing 471 patients with post-acute completer data and 236 participants with follow-up completer data. CBT plus pharmacotherapy was generally more effective than CBT plus placebo at post-treatment for measures of anxiety disorder severity (Hedges' g = 0.59, 95% confidence interval: 0.29-0.90) and treatment response (OR: 1.95, 95% confidence interval: 1.25-3.03), but not at 6-month follow-up. Despite the relatively small number of studies, the fail-safe N suggested that the results are reliable. The largest effect sizes at post-treatment were found for panic disorder and generalized anxiety disorder. No differences were observed between self-report and clinician-administered measures. The reported effect sizes linearly decreased with publication year. In sum, there is preliminary evidence to suggest that adding pharmacotherapy to CBT is a useful short-term treatment strategy at least for some of the anxiety disorders.