A new class of beta-adrenergic blockers with the pharmacologic property of intrinsic sympathomimetic activity (ISA) is emerging for use in the treatment of hypertension. These agents decrease blood pressure and systemic vascular resistance, while the heart rate and cardiac output at rest are maintained. Beta blockers with ISA may be used in clinical situations where non-ISA beta blockers are relatively contraindicated, such as sinus bradycardia, sick sinus syndrome, Raynaud-like symptoms and chronic obstructive lung disease.