The pharmacokinetics of an alpha, beta-adrenoceptor blocker, amosulalol hydrochloride, were studied after i.v. and oral administration to rats, dogs and monkeys. After an i.v. dose (1 mg/kg), the plasma concentration-time curve fitted a two-compartment open model with terminal half-lives of 2.5 h in rats, 2.1 h in dogs and 1.8 h in monkeys. The order of plasma clearances for amosulalol was: rats greater than dogs greater than monkeys. After oral administration, the maximum plasma concentration was obtained at 0.5-1 h in rats (10-100 mg/kg) and dogs (3-30 mg/kg), and at 1.7-2.7 h in monkeys (3-10 mg/kg). A linear relationship between the area under the plasma concentration-time curve and dose administered was obtained for all three species. The systemic availabilities of the drug in rats, dogs and monkeys were 22-31%, 51-59% and 57-66%, respectively. After repeated oral administration (10 mg/kg) to dogs for 15 days, the pharmacokinetic parameters did not differ significantly from those on the first day.