Antibodies to a variety of foods, and in particular cereals, were measured in serum from 100 patients with acute psychoses and 100 elective surgical patients. For 13 out of 14 foods to which non-IgE antibodies were detected the schizophrenics had slightly more antibodies than the controls. There was an association between a possible secondary mania and the presence of IgE antibodies to wheat or rye. However, neither the schizophrenia nor the mania findings can be regarded as evidence for food allergy causing psychiatric disorder, since the immunological findings in both cases may represent consequences of the illnesses or their treatment, rather than causes of the illness.