Two siblings, born to healthy non-consanguineous parents, were found to be affected with congenital progressive severe myopathy. Muscle biopsy revealed fiber type disproportion with no other histological abnormalities, thus confirming the diagnosis of congenital fiber type disproportion and suggesting an autosomal recessive mode of inheritance. This, to our knowledge, is the first reported family in which a strict histological diagnosis of congenital fiber type disproportion has been made and an autosomal recessive mode of inheritance shown.