The author discusses the use of the psychoanalytic method in drug addiction, provided the drug habit is controlled. The dynamics of drug addiction are described, using the theoretical concepts of Melanie Klein. It is closely related to manic-depressive illness but not identical with it. The addict uses manic and depressive mechanisms which are re-enforced and altered by the drug; the drug has both a symbolic meaning and a pharmacotoxic effect. The weak ego of the addict cannot bear the pain of depression and early resorts to manic mechanisms which can only be achieved with the help of drugs. The drug addict is mainly fixated at the paranoid-schizoid position although he has partially reached the depressive phase. the weakness of the addict's ego is related to the severity of his ego splitting; the prognosis in therapy depends on the extent to which the analysis can help the patient integrate the split-off parts of the self. An extensive case report is presented.