Abstract Four cases of paroxysmal ventricular tachycardia are reported. One attack lasted for twenty-six days without interruption and, although associated with myocardial infarction, ended with complete recovery after oral administration of a large, single dose of quinidine sulfate. Another attack, which showed bidirectional ventricular complexes due to digitalis intoxication, was treated in this manner, and recovery followed. In two of the four cases there was no evidence of organic heart disease. The electrocardiographic changes associated with and following a paroxysm of ventricular tachycardia are discussed. The advantage of oral administration of a large, single dose of quinidine sulfate is emphasized.