There is evidence that apoptotic cell death mechanisms contribute to muscle fiber loss in dystrophin‐deficient muscle but there is little knowledge about the final degrading events of muscle fiber apoptosis. In muscle biopsy specimens from 14 patients with a dystrophinopathy (10 patients with DMD, two with Becker MD, two DMD carriers), expression of APAF‐1 and caspase‐9, upstream members of the apoptotic protease cascade, as well as of the downstream executioners caspase‐2, ‐6 and ‐7, were studied by immunohistochemistry and Western blots. Besides predominant immunoreactivity in regenerating muscle fibers, which may contribute to apoptotic events during new muscle fiber formation, caspase‐9, ‐6 and ‐7 displayed upregulation in non‐regenerating, light microscopically intact but atrophic muscle fibers. Western blot analyses confirmed the upregulations. These findings indicate that, once activated, caspase‐9 initiates a proteolytic, muscle fiber degrading cascade involving the downstream executioners caspase‐6 and ‐7. However, lacking coexpression of APAF‐1 suggests the existence of other pathways of caspase‐9 activation than through the “apoptosome” in dystrophinopathies.