Neurodegenerative, neurological, and psychiatric diseases (NNPDs) significantly contribute to disability and mortality worldwide. Despite numerous studies, only few effective therapeutic methods and drugs have been found so far even for the most common diseases, such as Alzheimer’s and Parkinson’s diseases. The lack of effective therapeutic methods is mainly explainable by the absence of relevant in vitro model systems to study pathological phenotypes at the cellular and molecular levels. Induced pluripotent stem cells are a unique source of different types of patientspecific neurons that can reproduce in vitro the specific features of individual diseases. In this chapter, the cell models based on patient-specific induced pluripotent stem cellderived neurons and their use in the search for new drugs and toxicological studies are described in detail. In addition, the utility of genome engineering for the creation and study of cell models for NNPDs is discussed.