The goal of treating hypertension is to maximize therapeutic efficacy without untoward side effects. The accepted approach is to start treatment with a low dose of a single drug and then titrate it upward as needed to achieve a better therapeutic effect. However, higher doses of administered individual drugs increase the frequency and severity of side effects. A rational combination of individual drugs administered in low doses is preferable because it is associated with a high degree of efficacy, low incidence or severity of side effects, and high patient compliance. The most commonly used drug combinations are as follows: (1) diuretics with potassium-sparing agents; (2) beta-adrenergic blockers with diuretics; (3) angiotensin-converting enzyme inhibitors with diuretics; (4) angiotensin II receptor blockers with diuretics; and (5) angiotensin-converting enzyme inhibitors with calcium-channel blockers.