Recent morphometric studies indicate that both right and left temporal lobe volumes are reduced in schizophrenic patients. Subsequent studies suggested that this volumetric reduction is the result of focal or multifocal gray matter abnormalities. Since in early life brain growth or lack thereof influences the overlying skull configuration, we attempted to elucidate the time of onset of the temporal lobe lesion in schizophrenic patients by quantifying both the volume and shape of their middle cranial fossa. Computerized tomographic scans of 17 schizophrenic patients and an equal number of age-matched controls were digitized using a LOATS image analysis system. The middle cranial fossa was manually outlined and software routines allowed the quantification of volume and shape parameters. Our results showed that no significant differences were present between schizophrenic patients and controls. If the bilateral reduction in temporal lobe volumes in schizophrenic patients is the result of an early onset (e.g., developmental) lesion, the resultant foci of gray matter abnormality may occur distant to the base of the skull. Alternatively, tissue loss may be insufficient to alter the development of the overlying skull or to be detected by our methods.