Carrier risk assessment for Duchenne muscular dystrophy (DMD) is necessary to counsel women at risks of developing cardiomyopathy and having a child with DMD. Comprehensive molecular testing for dystrophin gene mutations has only been available since 20031; women counseled earlier have outdated risk assessments. We present a 5-generation family in whom results of familial mutation testing for DMD newly identified 10 obligate carriers and 28 women at risk to be carriers for DMD.