The effects of acebutolol and carbamazepine on ouabain-induced arrhythmias were investigated in rabbits. Ouabain produced ventricular arrhythmias which persisted for 7-8 min at the mean dose of 69 ± 1.3μg/kg. Ouabain arrhythmias were converted to normal sinus rhythm by administration of acebutolol or carbamazepine singly but lower dosages increased the recovery time. And then, ouabain arrhythmias were effectively converted to normal sinus rhythm and prevented by combined administration of carbamazepine and acebutolol. Each of the combined doses was ineffective when given singly. From the above results, it may be concluded that carbamazepine and acebutolol inhibited the ouabain-induced arrhythmias depending on the level of dosage and showed synergistic interaction.