Some pharmacokinetic interactions between digoxin and amiodarone were studied in experiments on rabbits. An increase of digoxin serum levels was established in amiodarone-treated rabbits (amiodarone 30 mg/kg s. c. for five days administered alone or together with digoxin). The calculated elimination half-life(t1/2) and the area under the curve (AUC) of digoxin were increased and the digoxin clearance was decreased, being most pronounced in animals receiving a combination of amiodarone and digoxin for five days. Changes were observed neither in the digoxin toxicity in amiodarone-treated guinea-pigs nor in the serum levels of T4, T3 and TTH. The possible mechanisms of the digoxin-amiodarone interactions are discussed.