Adverse effects of psychotropic medication on breast-fed infants have not been studied in controlled and systematic research. Existing information comes from small case series and single case reports. These limited data confirm that psychotropics are excreted into breast milk and that the infant is exposed to them. In recent decades sufficient data have accumulated to allow psychiatrists to prescribe tricyclic antidepressants, selective serotonin reuptake inhibitors, conventional antipsychotics, carbamazepine and sodium valproate to breast-feeding mothers with safety. There are not sufficient data on atypical antipsychotics to allow women to breast-feed safely. Mothers on clozapine or lithium should not breast-feed. It is good practice to recommend that breast-feeding mothers requiring psychotropic medication be on a low dose of one single drug. Future research taking account of maternal mental health, psychopharmacological factors, infant physiological environment and individualised risk/benefit assessment will yield clearer responses to this complex issue.