A case is reported of a 28-year-old woman with central core disease who prior to muscle biopsy was diagnosed to have muscular dystrophy. Histologic evaluation confirmed a diagnosis of central core disease, a nonprogressive or slowly progressive disorder of voluntary muscle belonging to a group of muscle diseases called benign congenital myopathies. The clinical and pathologic features fo this benign disorder are reviewed. Two sons were examined and found to be normal.