The present invention provides an inhibitor of intracellular protein degradation for use in the treatment and prevention of muscular dystrophy in a mammal. In particular, the invention provides an autophagy inhibitor and/or an inhibitor of the ubiquitin-proteasome system (such as a proteasome inhibitor) for use in the treatment and prevention of muscular dystrophy (such as congenital muscular dystrophy [e.g. MDC1A) and Duchenne muscular dystrophy [DMD]). The invention further provides corresponding methods of treatment and prevention of muscular dystrophy.