Despite the trend towards lower neuroleptic dosing in the treatment of psychosis, there continue to be patients who are administered doses that are higher than recommended. Thirty-six acutely psychotic patients receiving parenteral haloperidol were evaluated by the Brief Psychiatric Rating Scale, the Schedule for Affective Disorders and Schizophrenia-Change Version, and the Nurses' Observation Scale for Inpatient Evaluation, as well as by drug levels in plasma. Patients were compared on the basis of total haloperidol dose in the first 24 hours: regular dose (RD: 10-30 mg) and high dose (HD: 40-80 mg). At baseline, patients in the HD group scored significantly higher on the Brief Psychiatric Rating Scale factor Hostile-Suspiciousness and the Nurses' Observation Scale for Inpatient Evaluation factor Irritability. Assignment to regular-dose and HD groups could not be accounted for on the basis of age, gender, weight, or duration of illness. Moreover, drug levels in plasma indicated that the HD patients did not require higher doses on the basis of differences in haloperidol levels.