Duchenne muscular dystrophy is caused by mutations in the dystrophin gene. As in humans, zebrafish dystrophin is initially expressed at the peripheral ends of the myofibres adjacent to the myotendinous junction and gradually shifts to non-junctional sites. Dystrophin-deficient zebrafish larvae are characterised by abundant necrotic fibres being replaced by mono-nucleated infiltrates, extensive fibrosis accompanied by inflammation, and a broader variation in muscle fibre cross-sectional areas. Muscle progenitor proliferation cannot compensate for the extensive skeletal muscle loss. Live imaging of dystrophin-deficient zebrafish larvae documents detaching myofibres elicited by muscle contraction. Correspondingly, the progressive phenotype of dystrophin-deficient zebrafish resembles many aspects of the human disease, suggesting that specific advantages of the zebrafish model system, such as the ability to undertake in vivo drug screens and real time analysis of muscle fibre loss, could be used to make novel insights relevant to understanding and treating the pathological basis of dystrophin-deficient muscular dystrophy.