At least 5-10 per cent of the Danish population will during their lifetime experience more than one episode of major depression but only a minority of this group will receive the necessary and sufficient prophylactic treatment against their illness. Randomised controlled studies have shown that the majority of commonly used antidepressant drugs, new as well as old ones, possess prophylactic efficacy. Thus, treatment efficacy is not a major problem but the treatment efficiency in everyday clinical practice is unsatisfactory. This is partly due to a lack of relevant treatment facilities for psychiatric patients, partly to a lack of knowledge among patients and their relatives but also among doctors of the indications for prophylactic treatment against recurrent depression and the technical issues involved. A short practical guideline for prophylactic treatment against recurrent depression will appear from the article.