Environmental risk factors for the development of schizophrenia include infections during the perinatal period or later in life with Toxoplasma gondii (TG) being one of the candidate agents. A recent review (Torrey and Yolken, 2003) on TG in schizophrenia and other serious mental disorder reported higher antibodies to TG in patients compared to controls in 18 of 19 studies, one having been conducted by the investigators group. In a second, independent study on first-episode schizophrenia (n=56) and control subjects (n=32), sera were sampled and standard instruments used to assess diagnoses and psychopathology, respectively to screening controls.