We assessed the efficacy and safety of a botanical anxiolytic, Kava kava (Piper methysticum), in treating generalized anxiety disorder (GAD). Thirty-seven adults with DSM-IV GAD were randomly assigned to 4 weeks of double-blind treatment with kava or a matching placebo. Weekly efficacy assessments [Hamilton Anxiety Scale, Hospital Anxiety and Depression Scale (HADS), Self Assessment of Resilience and Anxiety (SARA)] and safety evaluations were conducted. Improvement was observed with both treatments but no differences were found in the principal analysis. Post-hoc analyses revealed significant differences based on baseline anxiety severity, whereby kava was superior on the SARA in low anxiety and placebo was superior on the HADS and SARA in high anxiety. Both treatments were well tolerated. Although kava was not superior to placebo, it would be premature to rule it out as efficacious in GAD.