Abstract We previously found autoantibodies against platelets in schizophrenic patients. One of the platelet proteins that bind these antibodies is enolase. Here, we describe the isolation and sequencing of an immunoreactive peptide after enzymatic digestion of enolase. The 3-D structure of enolase indicates that, unexpectedly, this peptide is buried inside the protein. However, 3-D surface analysis leads to the identification of a conformational epitope that resembles the binding peptide and might constitute a specific binder of the autoantibodies. In a screening of antibody binding with the peptide LVVGLCK, we found in 50 serum samples of controls a mean of O.D.=0.46; s=±0.21 relative enzyme immunoassay units, while in sera of 39 schizophrenic patients, we found a mean of O.D.=1.47; s=±0.65; P<0.0001. Furthermore, an inverse correlation was observed between duration of schizophrenia and the level of the detected autoantibodies. A screening of autoantibodies in sera of various mental disorders with this peptide is currently in progress.