Cerebrospinal fluid contains proteins and metabolites of brain origin and was extensively studied in psychiatry in the 1970's with few definitive results. We have recently found 40% reduced protein levels of GSK-3beta in schizophrenia in postmortem prefrontal cortex, but our attempt to develop a diagnostic marker using peripheral lymphocyte GSK-3beta was not successful. In this study we aimed to find whether the reduction in brain GSK-3beta is reflected in CSF of schizophrenia patients. We report a significant reduction in CSF GSK-3beta protein levels in six schizophrenia patients compared to seventeen healthy subjects. Our results corroborate other studies in which CSF protein levels reflect the alteration found in these proteins in schizophrenia patients' postmortem brain.