Centronuclear myopathy (CNM) is a rare congenital myopathy that is characterized by centrally placed nuclei in the muscle fibers. Three forms of the disease are clinically recognized. The severe neonatal form, the childhood onset form, and an adult-onset form. We report a 50 year old male patient with centronuclear myopathy (CNM) in whom the disease manifested itself in the fifth decade of life without any family history of such illness.