A comprehensive neuropathology of schizophrenic psychoses has not yet been established. According to the findings of clinical investigations, neurohistological studies mainly focused on limbic structures, the prefrontal cortex and the anterior cingulate cortex. The results of morphometric and stereological studies based on the classical neuropathological techniques are controversial and point to the necessity for a differentiated characterization of the morphological features of neurons. Therefore, methods of neurobiological fundamental research are employed for the detailed demonstration of the different neuron types that constitute cortical circuits. Using these techniques, the schizophrenic cortex is shown to contain a variety of characteristic alterations which are discussed in the light of hypotheses favoring a maldevelopmental pathogenesis of schizophrenic psychoses which can be looked upon as neuronal system disorders.