The influence of procainamide, N-acetylprocainamide, verapamil or propranolol on hemodynamic parameters in rabbits was studied during ketamine anesthesia. Using radioisotopic methods the following parameters were estimated: cardiac output, stroke volume, total peripheral resistance, renal and hepatic blood flows, arterial pressure and heart rate. During ketamine anesthesia the inhibitory effect of verapamil on peripheral resistance was intensified; after administration of the rest of antiarrhythmic drugs the decrease of peripheral resistance was not observed in the animals without general anesthesia. During ketamine anesthesia the negative chronotropic effect of N-acetylprocainamide was decreased, but the negative chronotropic effect of procainamide was intensified. Procainamide administration during ketamine anesthesia markedly decreased renal blood flow. Propranolol given without anesthetic, as well as given together with ketamine markedly decreased hepatic blood flow.