We describe a 40-year-old male case with centronuclear myopathy showing a unique clinical picture of generalized muscular pseudohypertrophy. CT scan, ultrasound imaging and histopathological studies of muscles revealed that muscle enlargement in this case might be caused by marked intrafascicular fatty infiltration. It is suggested that muscular pseudohypertrophy may occur in adult centronuclear myopathy cases with a long clinical course and that CT and ultrasound scans are very useful for the evaluation of diseased muscles.