The pharmacokinetics of recombinant hirudin (rec-hirudin, Ciba-Geigy, CGP 39 393) in healthy volunteers after iv administration was investigated on the basis of the data from Jive different studies. A total of 77 plasma profiles following a single iv bolus dose of either 0.1, 0.3, 0.5, or 1 mg/kg of rec-hirudin was used for the evualation. Plasma concentrations and especially AUC were proportional to the dose. Kinetics of rec-hirudin after a bolus iv injection were best described by a three-compartment open model. Mean apparent terminal half-life was 2.8 hr and the total clearance 0.138 L/hr per kg.