Objective: A cortical gray matter deficit has been found in cross- sectional studies of patients with chronic schizophrenia. The purpose of this study was to examine whether this deficit is present early in the course of illness. Method: The authors measured cortical gray matter volume on magnetic resonance images acquired within 6 months of onset of illness from 22 patients with first-episode schizophrenia and 51 age-matched comparison subjects from the Stony Brook First Episode Study. Results: A significant cortical gray matter deficit and lateral ventricular enlargement were found in schizophrenic patients relative to the comparison group. Conclusions: The presence of the cortical gray matter deficit close to onset of illness supports the role of preexisting structural brain deficits in the genesis of schizophrenia.