The artice discusses the role of chiral drugs in the modem pharmacology. We describe differences in the receptor affinity, the pharmacokinetics, the efficacy and adverse effects between single enantiomers of exemplary drugs with special emphasis put on drugs used in psychopharmacology e.g. escitalopram, S-enantiomer of citalopram. Escitalopram, the most selective serotonin reuptake inhibitor on the market, was introduced to the clinic for the treatment of depression and panic disorder in 2001. The article explains the mechanism of action and pharmacokinetic profile of escitalopram in detail. Moreover, we present the data from preclinical and clinical studies indicating the antidepressant potential and efficacy of escitalopram.