A pharmacokinetic study of droperidol was performed in ten anesthetized patients receiving an intravenous bolus dose of 150 micrograms/kg of droperidol. Plasma concentrations were measured using a specific radioimmunoassay method. The pharmacokinetics of droperidol can be described according to a three-compartment open model. The mean (+/- SD) half-life for the rapid (t 1/2 pi) and slow distribution t 1/2 alpha) phases was 1.4 +/- 0.5 min and 14.3 +/- 6.5 min, respectively. The mean elimination half-life, t 1/2 beta was 103.8 +/- 20.2 min. The mean (+/- SD) total body clearance was 14.1 +/- 4.4 ml X min-1 X kg-1, and the total apparent volume of distribution (Vd beta) was 2.04 +/- 0.50 l/kg. The short terminal half-life of droperidol does not correlate with the well-known, relatively prolonged duration of its pharmacologic action.