Many studies have established that birth dates during the winter and early spring months are more common in schizophrenic patients than in the general population. It has been hypothesized that children born in winter are more likely to be exposed to environmental factors which could lead to the development of schizophrenia later in life. Another finding of interest has been the demonstration in brain-imaging studies that mild ventricular enlargement is more often found in schizophrenic patients than in healthy control subjects. In the present report, an increased incidence of ventricular enlargement was found in schizophrenic patients born in the winter months. Although the relationship between seasonality of birth and brain abnormalities is unclear, these phenomena could be partly linked.