This chapter concentrates on the types of muscular dystrophy (MD) such as X-linked muscular dystrophies, autosomal recessive muscular dystrophies and autosomal dominant muscular dystrophies. Specific immunoanalysis of muscle biopsies may be informative in directing genetic analysis in some cases, but the gold standard for diagnosis in the majority of the muscular dystrophies, and certainly for genetic and prognostic counseling, has become the application of specific DNA-based tests. The dystrophinopathies, including Duchenne and Becker muscular dystrophy, are among the most common in all populations. The autosomal recessive muscular dystrophies fall into two main groups, the congenital muscular dystrophies and the autosomal recessive forms of limbgirdle muscular dystrophy. The autosomal dominant types of MD share several features that are crucial for genetic counseling; namely, frequently highly variable phenotypes within or between different families, the high incidence of new dominant mutations, and the need to address the issue of presymptomatic testing with sensitivity.