Bone-marrow cells have the potential to differentiate into other cell types such as muscle fibres, and can be transplanted into acutely or chronically damaged muscle as a way of delivering normal dystrophin (the protein that is defective or missing in Duchenne’s muscular dystrophy) to the skeletal and heart muscle of mdx mice, an animal model for this disease. But the corrective potential of this approach has been hard to estimate against the high background of muscle fibres that spontaneously revert to synthesizing dystrophin, a feature of the original mdx mutation. Here we test the long-term efficacy of bonemarrow transplantation in a different mdx mutant which is free of this problem and find that it has no impact on murine muscular dystrophy.