The authors found normal monoamine oxidase (MAO) activity in 40 acute schizophrenic patients, in contrast to previous reports of a genetically linked platelet MAO deficit in chronic schizophrenia. Variations in MAO activity were not significantly associated with the 65 clinical variables analyzed, although there was a tendency for patients in the low-MAO group to have more severely impaired reality testing, more paranoid and grandiose delusions, better prognostic scores, and less restlessness.