In seven patients with symptomatic atrial fibrillation and uncontrollable ventricular rates, selective catheterization of the atrioventricular (AV) nodal artery was performed to chemically destroy the AV node. Ethanol at a concentration of 96% and a dose of 0.5-2 ml was used after selective catheterization of the AV nodal artery had demonstrated temporary AV block after the administration of isotonic iced saline. Complete AV block was produced in five patients and AV conduction was sufficiently modified to control symptoms in the remaining two patients. A minimal enzyme rise occurred in six patients. A severe complication in the remaining patient occurred when, after 2 ml ethanol in the AV nodal artery, occlusion developed in the midright coronary artery that led to an inferior wall myocardial infarction. It is concluded that the AV nodal artery can be selectively catheterized using presently available angioplasty techniques. Ethanol can be used to destroy the AV node and block AV conduction.