THE clinical efficacy of lithium therapy in mania has recently been confirmed. It has also been shown that lithium has a weak antidepressant action. In addition there is controversial evidence of its effect as a prophylactic agent in preventing depressive attacks.1 We have also noted that none of the current biological hypotheses in the affective disorders provides a satisfactory explanation for the clinical efficacy of lithium.2 Since 19553 it has been suggested that manic patients have a specific metabolism with regard to the handling of lithium and this has recently been stated again by workers in the United States.4 An acute study was not able to confirm these reports,5 but this study has been criticized regarding its lack of control of concomitant chlorpromazine treatment.6 However, we have not been able to show differences in the handling of lithium in different affective