The effectiveness of quinidine sulphate as a means of abolishing auricular fibrillation has led to the use of this drug in the treatment of other forms of cardiac arrhythmia. We report here our experience in using quinidine in paroxysmal and persistent tachycardia of ventricular origin. The action by which quinidine alters the mechanism in auricular fibrillation has been shown by Lewis and his co-workers1to depend chiefly on its tendency to break up a circus movement in the auricle. This occurs when the effect of quinidine in prolonging the refractory phase of auricular muscle predominates over its effect in slowing the rate of conduction of the rapidly circulating impulse. There is some reason to feel that the common forms of abnormal tachycardia may be due to a disturbance similar to that found in auricular fibrillations; i. e., to a circus movement. Particularly is this true of the rarer forms