Disopyramide is a new antiarrhythmic drug with a pharmacological profile of action similar to that of quinidine and procainamide. In a few controlled therapeutic trails and a large number of uncontrolled studies in patients with arrhythmias, often following a myocardial infarction, disopyramide has been relatively effective (more so in ventricular than in atrial arrhythmias) and usually well tolerated. In treating premature atrial and ventricular contractions, the best-studied area of its therapeutic use, disopyramide was superior to a placebo and of similar efficacy to but better tolerated than quinidine; the drop-out rate due to adverse effects of the disopyramide group (10%) being less than one-third that of the quinidine group (36%). In an open ward setting, disopyramide used prophylactically after myocardial infarction appeared to reduce both the incidence of reinfarction and the mortality rate, while in patients treated in coronary care units although the incidence of reinfarction was lower with disopyramide than with a placebo, the mortality rate was not significantly different. Further well-designed trials with adequate numbers of patients are needed before the routine use of disopyramide in infarct patients treated in either setting can be justified. Comparative studies are also required to determine if disopyramide has advantages over other antiarrhythmic agents in this area of use. Side-effects with disopyramide are usually a result of its anticholinergic activity, a dry mouth and difficulty in urination being the most common. Like other antiarrhythmic agents, disopyramide exerts a negative inotropic action on cardiac muscle, and development of acute heart failure has been reported. Development of worsening of heart block and hypotension have also occurred. Disopyramide is largely excreted unchanged and dosage should be reduced in patients with impaired renal function, in accordance with creatinine clearance values.