As an initial approach to computer-automated segmentation of cerebral spinal fluid (CSF) vs. brain parenchyma in MR scans, and the transformation of these data sets into volumetric information and 3D display, we examined the ventricular system in a sample of ten chronic schizophrenics with primarily positive symptoms and 12 normal subjects. While no significant differences were noted between groups on volumetric measures of ventricular brain ratio or lateral ventricle size, normals showed a pattern of left greater than right lateral ventricular volume asymmetry not present in the schizophrenics. Within the schizophrenic group, departure from the normal left greater than right pattern was highly correlated with thought disorder.