As with all antidepressant therapies, there is variability among major depressed patients in terms of response to selective serotonin reuptake inhibitor (SSRI) treatment. Of the factors causing this inter-individual variability in response, differences in genetic components may play a major role. Some very recent research has focused on the associations between genetic polymorphisms in candidate genes related to SSRI therapeutic action. Several genetic polymorphisms have been associated with therapeutic SSRI response, including genetic variants of the serotonin transporter, serotonin- 2A-receptor, tryptophan hydroxylase, brain-derived neurotrophic factor, G-protein beta3 subunit, interleukin-1beta and angiotensin-converting enzyme, however, these positive findings have not been replicated in all studies. In this article, the SSRI pharmacogenetic studies for major depression are reviewed, and recommendations proposed for future study.