Duchenne muscular dystrophy (DMD) is a severe muscle wasting disease caused by the lack of dystrophin expression. To restore dystrophin expression, gene therapy is a promising strategy. The most efficient vector for systemic delivery to the skeletal muscles, diaphragm, and the heart is adeno-associated virus (AAV). However, full-length dystrophin is too large to be packaged into AAV. We are developing strategies to restore dystrophin function in the heart.