1. The normal structure of the superior temporal gyrus (STG) has been elucidated from human and non-human primate research. This brain region is structurally complex, contains several distinct cellular regions and the area known as the planum temporale. 2. The STG connects with heteromodal neocortical regions and temporolimbic areas. 3. Functional studies of the normal STG in animals and in humans, using electrophysiology and PET/fMRI, emphasize the STG's role as part of a cortical network important in the interpretation, production and self-monitoring of language. 4. There is evidence for structural abnormalities of the STG in schizophrenia including both volume reductions and disturbances of normal asymmetries. 5. Functional studies of this region in schizophrenic patients, including measurements of evoked potentials and of bloodflow, are abnormal, especially when patients perform language tasks or experience hallucinations. 6. This structural and functional pathology in the STG probably represents one example of a more general disruption in schizophrenia of the neocortical network of which this region is an essential part. This disturbance may be closely associated with the symptoms of formal thought disorder and of auditory hallucinations commonly seen in the disorder.