Angiotensin-converting enzyme (ACE) inhibitors and calcium antagonists are important classes of antihypertensive agents. Within their respective classes, ACE inhibitors and calcium antagonists share common pharmacokinetic properties, but in contrast to ACE inhibitors, some calcium antagonists may cause a significant increase in plasma digoxin concentrations. Clinically, both classes of agents have been shown to be safe and effective in large-scale, long-term clinical trials. ACE inhibitors appear to be very well tolerated and may be associated with fewer adverse effects than some calcium antagonists. ACE inhibitors appear to blunt diuretic-induced hypokalemia, hypercholesterolemia, hyperuricemia, and hyperglycemia. Both classes of agents can be used safely in patients with renal disease, diabetes mellitus, peripheral vascular disease, and chronic obstructive pulmonary disease. They may also be used in the elderly. While ACE inhibitors are particularly useful in hypertension accompanied by congestive heart failure, calcium antagonists can be very useful when angina pectoris is present in the hypertensive patient.