Brain morphology was quantified with magnetic resonance imaging (MRI) in adult patients with congenital rubella who also had schizophrenialike symptoms. MRIs were compared with those of adult early-onset schizophrenic patients without congenital rubella and age-matched healthy control subjects. The rubella patients had significantly smaller intracranial volumes and shorter stature than the schizophrenic patients or the controls; however, both patient groups had smaller cortical gray matter, but not white matter, volumes than the control group, even when the MRI volumes were corrected for head size and age. In addition, both patient groups showed significant enlargement of the lateral ventricles but not cortical sulci when compared with expected values of normal adults of the same age and head size. Overall, the pattern of dysmorphology was identical in the rubella and the schizophrenic groups. The observations in the rubella group are consistent with a developmental lesion that limits full brain growth, with the small intracranial volume due at least in part to a severe cortical gray matter volume deficit. Thus, the brain dysmorphology of congenital rubella may provide an instance of prenatal viral infection that models the schizophrenic pattern and provides indirect support for a developmental hypothesis of the neuropathogenesis of schizophrenia.