Research into neurogenesis, i.e., the growth of new neurons in the adult brain, is leaving the area of pure basic science and gaining relevance for clinical disciplines such as psychopharmacology and molecular psychiatry. Neurogenesis is proposed to play a crucial role in psychiatric disorders which exhibit degenerative alterations, neural maldevelopment, and changes in neural plasticity as potentially important pathophysiological factors. Especially in dementia, drug addiction, and schizophrenic and affective psychoses, disruption of adult neurogenesis could thus represent a considerable pathogenetic element. Interestingly, several psychotropic drugs (e.g., antidepressants, atypical antipsychotics) are able to modify neurogenesis significantly. Further elucidation of the importance and implications of neurogenesis may concomitantly result in better understanding of the etiopathogenesis of mental disorders and increased knowledge of the mechanisms of action of psychotropic substances. Furthermore, this may support the development of promising innovative therapeutic approaches in clinical practice.