Plasma mucoprotein concentrations were determined in psychotic and normlal individuals. Mucoprotein determinations were done by the method described by J. R. Winzler. In this study of 52 physically healthy schizophrenic patients, abnormally high plasma mucoprotein concentrations were encountered in those who exhibited readily or repeatedly the state of excitement, restlessness, incoherence, stupor, hostility and the like. The elevated mucoprotein levels were observed in several manic-depressives. general paretics and other organic psychotics. The neurotics showed normal concentrations of mucoproteins in their plasmas.