Immunoreactive [I] prostaglandin[PG]E and thromboxane[Tx]B2 were measured in cerebrospinal fluid from patients with schizophrenia and from control subjects. Schizophrenics had higher I-PGE concentrations than healthy controls, patients classified as neurotics and patients admitted for neurological investigation. I-TxB2 concentrations were similar in all 4 groups. At least in some forms of schizophrenia there may be an alteration of PG synthesis or metabolism.