Background : Over a thousand years of clinical preparation of Ephedrain traditional Korean medicine has confirmed effectiveness and security. Recently. Ephedra-containing herbal preparations to treat obesity are common. The aim of this study is to identify effects of Ephedra on psychological anxiety. Objectives : To determine effects of Ephedraon psychoactivity and autonomic nervous system. Methods : The study design was a double-blind randomized controlled trial. The subjects of this study were healthy adults. They were allocated to either the Ephedragroup (N =66) or the placebo group (N =32), Ephedra(8 g) or a placebo in similar opaque capsules was given twice a day for 2 weeks. Anxiety score was estimated with State-Trait Anxiety Inventory before first and after last medication. 36 of the Ephedragroup and 24 of the placebo group finished the trial and were analyzed. Paired samples T-test and independent samples T-test were applied to statistical analysis. Results : The following result was obtained: After taking Ephedra. state anxiety increased significantly. In the placebo group. both state and trait anxiety increased although significance was not reached. Conclusions : It is concluded that the intake of Ephedraplays a significant role in the increase of anxiety in healthy adults. It is suggested that anxiety level change should be considered when using Ephedra in clinics.