Affective disorders, including unipolar (UP) disorder and bipolar (BP) disorder are among the most important causes of death and disability worldwide and result in high costs in terms of morbidity as well as mortality. Although the etiology and pathophysiology is widely unknown, family-, twin- and adoption studies argue for a strong genetic determination of these disorders. These studies indicate that there is between 40-85% heritability for these disorders but point also to the importance of environmental factors. Despite the availability of a wide range of different drugs, about 30-50% of patients do not respond properly to acute treatment. Here we provide an overview of genetic drug response markers for affective disorder. Central in review is the question if individual therapeutic outcome for a given treatment can be predicted using genetic markers? An overview of pharmacogenetic and pharmacogenomic approaches is described for selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants (TCAs), and mood stabilizing drugs in relation to each of the major candidate genes for affective disorders.