The plasma concentration--time course of muscone in rats after a single i.v. administration fitted well to a two-compartment open model, and those in rabbits and dogs were all conformed to a three- compartment open model. Significant species differences were observed in the pharmacokinetic parameters among rats, rabbits and dogs, while no significant differences were found among the three dosages of 12, 18 and 24 mg/kg after i.v. administration to rats. In rats, the T1/2 beta was found to be 118.1-131.2 min. In rabbits and dogs, the T1/2 beta were 24.9 and 30.0 min, respectively and the T1/2 gamma were 331.9 and 366.4 min, respectively. In rats, rabbits and dogs, the Vss were 23.0, 51.7 and 7.3 L/kg, respectively, and the Vc were 2.33, 2.13 and 0.38 L/kg, respectively.