Angiotensin converting enzyme inhibitors are effective in the treatment of hypertension and congestive heart failure. Within the past two years, four new agents in this class-benazepril, fosinopril, quinapril and ramipril--have been approved in the United States for use in the treatment of hypertension. These agents have been shown to be as effective as the older angiotensin converting enzyme inhibitors in treating hypertension and, in limited trials, congestive heart failure. The side effect profiles of the new agents are similar to those of other agents in this class that do not contain a sulfhydryl group. Fosinopril has a unique route of elimination that may make it the preferred agent in patients with renal failure. Otherwise, the new angiotensin converting enzyme inhibitors have no proven clinical advantages over other available agents. However, at moderate to high doses, the new agents may be substantially less expensive.