Smooth pursuit eye movements (SPEM) were examined in 67 schizophrenic patients and 101 control subjects. Our study confirms that eye tracking in schizophrenic patients is impaired compared to that in controls. The similar pattern of distribution of SPEM abnormalities in Italian patients as in ethnically different populations strengthens the hypothesis that these abnormalities may be a biological marker for schizophrenia. We also examined the relationship between SPEM abnormalities and the ventricle-brain ratio (VBR), which is also considered useful for differentiating schizophrenic subgroups. Our preliminary results indicate that there is an inverse correlation between abnormal SPEM performance and ventricular enlargement, suggesting that these abnormalities mark distinct subgroups of patients.