Diltiazem is a calcium antagonist effective in the treatment of stable, variant and unstable angina pectoris and mild to moderate systemic hypertension, with a generally favourable adverse effect profile. It is also effective in terminating supraventricular tachycardia and in controlling the ventricular response to atrial fibrillation/flutter. Atrioventricular block, the risk of which may be exacerbated by concomitant beta-adrenoceptor antagonist therapy, occurs rarely as an adverse effect of diltiazem treatment. Diltiazem appears to exert complex cardioprotective effects which have been of benefit after intracoronary administration to patients undergoing coronary angiography and bypass procedures. In addition, long term diltiazem treatment has produced a significant reduction in subsequent cardiac events in patients with non-Q wave myocardial infarction. Thus, diltiazem is an effective and well-tolerated first-line or alternative treatment of patients with ischaemic heart disease, systemic hypertension, and supraventricular arrhythmias, with possible potential in limiting ischaemia-induced myocardial damage.