Various clinical and epidemiological data have suggested the possibility of infectious mechanisms in schizophrenia. In addition, lengthy prodromal psychiatric symptoms can presage the development of Creutzfeldt-Jakob disease, a prototypical prion disorder. Accordingly, the presence of human protease resistant prion proteins (PrPres) was assessed in postmortem frontal cortical and thalamic tissues from a prospectively accrued and well characterised sample of elderly patients with chronic, sporadic, "poor outcome" schizophrenia using a sensitive immunoblot assay. No PrPres was found in the brains of any of the cases, providing evidence against a role for abnormal prion proteins in the pathogenesis of schizophrenia.