Presents the case 27-yr-old female patient with generalized anxiety disorder who was treated with buspirone. During the treatment, the patient felt depressed, and decided to self-medicate with St John's Wort. During the 1st 3 wks of concomitant treatment, the patient described that the depressive symptoms were improved. However, after 2 mo of beginning the combination of St John's Wort and buspirone, she began to experience adverse effects consistent with serotonin syndrome.