Patients suffering from an acute episode of mild to moderate major depression and who had been treated successfully with Hypericum perforatum extract WS 5570 in doses of 600 mg/day or 1200 mg/day or with placebo for 6 weeks in a multi-centre, double-blind, randomized clinical trial, were asked to take part in a continuation treatment. Those participants with a HAMD total score decrease > or =50% during acute treatment were eligible for 4 months of double-blind continuation treatment with the same dose regimen. In total, 69, 68 and 24 (WS 5570 600 mg/day, 1200 mg/day and placebo) patients entered continuation treatment. Both WS 5570 groups showed an additional slight decrease of the HAMD total score by 0.8 (600 mg WS 5570/day) and 0.4 (1200 mg WS 5570/day) points during treatment phase, while patients in the placebo group deteriorated by 2.1 points. The incidence of adverse events was low in all therapy groups.