Abstract: The pA₂ values of six beta-adrenoceptive blocking agents in isolated rabbit atrium determined previously by the A-S (Arunlakshana-Schild) method ranked in decending order as: pindolol, propranolol, alprenolol, oxprenolol, atenolol and practolol. In this paper, the pA₂ values of the above six beta-adrenoceptive blocking agents were reestimated with computer programs. The results showed the declining order as: pindolol, oxprenolol, alprenolol, propranolol, atenolol and practolol. The agents within an underline indicate that their pA₂s are not significantly different (P>0.05), while separate underlines mean significant difference (P<0.05). Though the two methods did not contradict each other in this experiment, the objective statistical method with computer program would provide much more informations about the kinetics of the interaction of drug-receptors than those of the A-S method.Clark originally assumed that the effect was directly proportional to receptors occupied. This simplest model challenged by many authors seems valid in this experiment.