Objective: The delivery of biological markers for schizophrenia would greatly assist preventative strategies by identifying at-risk individuals who could then be monitored and treated in a manner with a view to minimising subsequent morbidity. This paper aims to present a selection of biological measures that may indicate risk of schizophrenia. Method: A selective and brief review is provided of intensively studied putative markers, including enlarged cerebral ventricles, dopamine D2 receptor density, amphetamine-stimulated central nervous system dopamine release, plasma homovanillic acid and smooth pursuit eye tracking dysfunction. Results: A number of biological measures have been reported to be correlated with schizophrenia. Conclusions: Presently, none of these measures has satisfactory performance characteristics in terms of predictive validity, noninvasiveness, ease of testing and low cost that would enable their widespread use. However, a few have potential for further investigation and development. © 2000, The Royal Australian and New Zealand College of Psychiatrists. All rights reserved.