The present article reviews the studies on genetic determinants for drug response to the treatment of depression. These investigations assess the individual differences in the pharmacokinetic mechanisms - such as the genetic variants of genes coding for drug-metabolizing enzymes - and in the pharmacodynamics, looking at the genetic variants of genes coding for drug targets. The authors conclude that the knowledge about the functional variants of the genes coding for antidepressant metabolizing enzymes such as CYP2D6, or genes coding for antidepressant targets such as the serotonin transporter protein (5-HTT), could assist in individualizing the selection of medication and dosage for depression treatment.