This section concerns itself with the entities of congenital myotonic dystrophy (DM1), a genetic disorder which can have both neonatal and infantile/childhood forms, and congenital inflammatory myopathies, which are thought to result from intrauterine infection or autoimmune process. These are rare but enter into the differential diagnosis of the other congenital myopathies and dystrophies as previously discussed (see Chapters 52–53). In particular, the diagnosis of congenital inflammatory myopathy is one of exclusion, as it must be distinguished from congenital muscular dystrophies which may have secondary inflammation [1].