In recent years neuroimaging techniques have revealed various cerebral and structural variances in patients with schizophrenic psychoses. The best established findings are the enlargement of the lateral ventricles and discrete structural deficits in temporobasal structures of the cortex. Neuropathological investigations have detected subcortical as well as cortical variances. Subcortically, the volume of the striatum and the globus pallidus have been found to be enlarged in schizophrenics. Among the cortical deviations, the cytoarchitectonic disturbances of the rostral entorhinal region have been well documented and are especially important. According to neuropathological criteria, they are derived from disturbances of prenatal cell migration within the central nervous system. Due to its close anatomical and functional connection with the hippocampal formation and its being the assembly point of all sensory cortical areas, disturbances of this area could seriously impede the processing and filtering of information within the limbic system. The other hitherto reported structural anomalies, such as the disturbance to the radial order of hippocampal neurons, and the abnormal structures in the frontobasal orbital regions and the rostroventral insula, could be connected to the disturbances of migration within the entorhinal region; the former could be secondary, but still prenatal developments. Well documented are the architectonic changes in the rostral cingulate gyrus which is itself connected with the entorhinal region via the Papez circuit. These findings are supported and supplemented by the results of epidemiological studies which indicate a disturbance of brain development during the second trimenon of the prenatal period. Viral infections (Influenza A2) of mothers during this critical period appear to play an especially important role.(ABSTRACT TRUNCATED AT 250 WORDS)