A number of clinical studies conducted over the past few years have indicated that whole extract of St John's wort (Hypericum perforatum L.) has antidepressant effects. The herbal antidepressant St John's wort offers promising results in the treatment of patients with mild and moderate depression (response rate of 60-70% estimated by analysis of pooled data). St John's wort preparations are well tolerated. Their use rarely leads to adverse drug reactions which, when they do occur, are mainly subjective symptoms (e.g. gastrointestinal, dizziness). The generally good tolerability of St John's wort preparations and the resulting high patient compliance in taking the prescribed medication, in conjunction with their efficacy in mild and moderate depression, make these preparations particularly suitable for use in outpatient practice. Tolerability is also very good in elderly patients. If a sufficiently high-dose course of treatment with St John's wort preparations (900 mg daily) does not lead to a clear improvement in depression after four to six weeks, therapy should be continued with an established ('classical') antidepressant.