Respiratory failure and heart failure are inevitable complications in Duchenne muscular dystrophy (DMD). Respiratory failure and heart failure undergo simultaneously and affect each other. After dissemination of mechanical ventilation, heart failure is the main cause of death in DMD. Regular assessment of cardiopulmonary function, early introduction of cardioprotective therapy and intensive respiratory care are the key issues in medical managements of DMD. In DMD, angiotensin converting enzyme inhibitors (ACEI) and angiotensin II type 1 receptor blockers (ARB) are used as the first line drugs. Beta-blockers (BB) are usually added to ACEI/ARB, when they cannot achieve sufficient effects. Although high dose of BB might be required for functional improvements, even a low dose BB can reduce cardiac events. Recent meta-analyses reported heart rate reduction is more important than BB dose for reducing mortality. Thus heart rate monitoring is essential for titration of BB. Tachycardia under optimal respiratory care can also be an indicator of BB. Although the introduction of BB is relatively safe under gradual dose-escalation from a low dose, hospitalization during uptitration should be considered in advanced cases.