This review describes the haemodynamic and electrophysiologic properties of diltiazem and shows how these effects may, in some clinical situations, favour the choice of this drug as an antianginal and antiarrhythmic agent. Compared to nifedipine and verapamil, diltiazem has the distinct advantage of being a negative chronotropic agent and thus has the potential of leading to a greater reduction in myocardial oxygen consumption; it does not affect cardiac output, left ventricular end diastolic pressure, and ejection fraction in patients with an adequately preserved left ventricular function; finally, it possesses a longer duration of action and fewer side effects, even at relatively high calcium entry blocking doses, than the other major calcium entry blockers.