Diltiazem hydrochloride is a benzothiazepine derivative calcium-channel blocker with proven antianginal and antihypertensive capabilities. Its primary mechanism of action is vasodilatation, which results in diminished vascular resistance and improved perfusion to various vascular beds and target organs. The antihypertensive efficacy of diltiazem in various demographic groups has been studied and compared with diuretics, beta-blockers, angiotensin-converting enzyme inhibitors, and other calcium-channel blockers. These studies have shown that the antihypertensive effect of diltiazem is similar to that of the other therapies. Diltiazem does not adversely affect electrolytes or carbohydrate or lipid metabolism, and it may have beneficial effects on the heart and kidneys. Diltiazem reduces myocardial hypertrophy and exerts antianginal effects on the heart through coronary vasodilation and reduction in the blood pressure double product. Diltiazem improves renal perfusion and attenuates proteinuria. These effects may be helpful in limiting the progression of renal injury. Overall, the efficacy and tolerability of diltiazem, as well as its salutary effects on the heart and kidneys, make it an important therapeutic consideration for patients with hypertensive disease.