Background: Although brain volume changes are found in schizophrenia, only a limited number of structural magnetic resonance imaging studies have exclusively examined antipsychotic-naïve patients. Aims: To comprehensively investigate multiple brain structures in a single sample of patients who were antipsychotic-naïve. Method: Twenty antipsychotic-naive patients with first-episode schizophrenia and 20 healthy comparison subjects were included. Intracranial, total brain, frontal lobe, grey and white matter, cerebellar, hippocampal, parahippocampal, thalamic, caudate nucleus and lateral and third ventricular volumes were measured. Repeated-measures analyses of (co)variance were conducted with intracranial volume as covariate. Results: Third ventricle volume enlargement was found in patients compared with the healthy subjects. No differences were found in other brain regions. Conclusions: These findings suggest that some brain abnormalities are present in the early stages of schizophrenia. Moreover, it suggests that brain abnormalities reported in patients with chronic schizophrenia develop in a later stage of the disease and/or are medication induced. Declaration of interest: None.