Myotubular myopathy, also known as centronuclear myopathy, is a congenital muscle disorder. Based on inheritance, different age of onset, severity of involvement and rapidity of progression, three major patterns have been described. X-linked myotubular myopathy is the most prevalent and severe type. Affected boys frequently die in the neonatal period due to respiratory failure. The characteristic muscle histopathologic finding is centrally positioned nuclei in most muscle fibers. To emphasize the importance of accurate diagnosis of the hypotonic newborn with respiratory distress, we present two cases, including one male and one female newborn, with generalized hypotonia, muscle weakness, and respiratory distress at birth diagnosed as myotubular myopathy by muscle biopsy. Anahtar Kelimeler : Yenidoğan, solunum güçlüğü, miyotübüler miyopati, Newborn, respiratory distress, myotubular myopathy