Background: The anatomical origin of the enlargement of the cerebral ventricles in schizophrenia is obscure. Methods: In this study, the volumes of the hemispheres and lateral ventricles were assessed in MRI scans of 43 formalin-fixed brains (23 from patients and 19 comparison subjects) using a spline ‘snake’ segmentation method. Results: A bilateral ventricular volume increase was found in schizophrenia. Whereas enlargement of the lateral ventricle (mean: 54%) as a whole was related to age of onset and was greater in females than in males, enlargement of the temporal horn (mean: 54%) was not strongly related to age of onset or sex. Lateral ventricle volume was negatively correlated with STG, fusiform and parahippocampal volume in schizophrenia. Hemispheric volumes were unchanged. Conclusions: The differing correlates of the components of ventricular enlargement suggest a degree of selectivity of the disease process with a focus in the temporal lobe.