TENORMIN, known generically as atenolol, is a prescription medication that belongs to a class of drugs known as beta-blockers. It is primarily used to treat high blood pressure (hypertension) and to prevent angina (chest pain). TENORMIN works by blocking the action of certain natural chemicals in your body, such as epinephrine, on the heart and blood vessels. This effect lowers the heart rate, blood pressure, and strain on the heart. Atenolol can also be used to help prevent heart attacks and to improve survival after a heart attack. It is often chosen for its specific action on the heart, making it a preferred option for patients with certain heart conditions who need a beta-blocker.