According to the neurodevelopmental theory, etiological and pathological factors of a disease occur long before its symptoms. Cessation of the normal course of neuronal development causes disorders in their function and neuronal network, whereas after latency it leads to clinical manifestation of symptoms. In neurodegenerative diseases the specifically pathophysiological process, usually conditioned genetically, impairs selectively the ”sensitive” population of neurons and causes neuropathological symptoms and changes. The course and nature of these dysfunctions depend on superimposing of the pathological process on the normal process of development and puberty, and on individual plasticity and compensatory processes in the central nervous system. Schizophrenia meets some of these criteria, but it does not fit into the narrow definition of neurodegenerative diseases. So far no histopathological, immunocytochemical changes have been found, which would allow to identify the disease. However as early as during the first episode, most patients exhibit some characteristics of clinical deterioration, afterwads the status of most of them gets stabilized at a certain level of cognitive and social functioning, whereas in some patients the severity of the disease and cognitive dysfunctions gradually progress. The progression of schizophrenic process is also reflected in evolution of symptoms in the course of the disease, in biochemical and anatomical changes of the central nervous system. Presently, the neurodegenerative hypothesis of schizophrenia cannot be rejected. It may appear true only in a part of the patients with specific course of the disease, and in some cases neurodegeneration may be superimposed on neurodevelopmental disorders.