In their study of mortality in patients with affective disorder commenced on lithium, Brodersen et al (Reference Brodersen, Licht and Vestergaard2000) paint an unfairly negative picture of the efficacy of lithium. They compared mortality in patients with affective disorders who were started on lithium, irrespective of their compliance with treatment, with that of the general population. This gives a false impression that lithium could increase mortality. To assess the efficacy of lithium, they should ideally have compared those who were compliant with the treatment with those who were not and also with the general population, as Kallner et al (Reference Kallner, Lindelius and Petterson2000) did. The latter study clearly demonstrates that even though affective disorder patients have an increased mortality compared with the general population, lithium has a definite antisuicidal effect. Moreover, in unipolar depression, suicide rates increased only after patients discontinued lithium. These two studies also show how the methodology can affect the findings.