The purpose of this paper is to review the results of quinidine therapy in 274 unselected patients with established auricular fibrillation. There is still a diversity of opinion regarding the indications for quinidine and the factors influencing successful therapy.1-6 The risks of quinidine also present problems. The occurrence of embolism after conversion to sinus rhythm has probably been exaggerated. Can the routine use of anticoagulants further reduce the danger? How frequent is syncope, and how efficient are immediate measures, such as artificial respiration, closed-chest cardiac massage, and appropriate drugs, in preventing sudden death, ascribable to quinidine? Methods During 6 years, all patients in our medical department with persistent fibrillation were treated with quinidine. The only contraindication was total atrioventricular block. All patients were digitalized, and the signs of congestive heart failure were reduced as far as possible by salt restriction, mercurial diuretics, aminophylline, etc., before conversion was attempted. Anticoagulants