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Aim: To study the pharmacokinetic (PK) properties in rabbits treated with N-Ile1-Thr2-63-desulfato-r-hirudin (rH) newly developed in China by means of bioassay in order to provide preclinical experiment basis for its development as a novel anticoagulant agent. Methods: rH plasma concentration was determined using bioassay based on ex vivo antithrombin activity of rH. Normal rabbits received iv rH 4.0, 2.0 and 1.0 mg/kg or sc rH 2.0 mg/kg, respectively. The rabbits with acute severe renal failure were given iv rH 2.0 mg/kg. Results: The bioassay described in this paper met requirements for study of PK in rabbits. The major PK parameters after iv dosing were as follows: t1/2β 58.4～59 min. Vd 0.09～0.12 L/kg, CL 0.0035～0.0040 L/(kg.min);AUC were proportional to the doses, t1/2 and CL did not change significantly with the doses. The sc bioavailability reached 94%. The rabbits suffering from acute severe renal failure presented 11-fold longer t1/2β and 13 -fold greater A UC than normal healthy rabbits.Conclusion: rH exhibited rapid elimination, distribution was only limited to extracellular space and good absorption from sc site.The excretion ofrH by kidneys played a very important role in the elimination of rH. The PK ofrH could be described by the twoand one-compartment model after iv and sc dosing, respectively, and followed linear kinetics.