Glycogen storage disease type II (GSDII), also referred to as Pompe disease or acid maltase deficiency, is a rare inherited condition caused by a deficiency in acid alpha-glucosidase (GAA) enzyme activity (Tinkle andLeslie. GeneReviews, 2008. http://www.genetests.org). The condition is often classified by age of presentation,with infantile and late onset variants (Laforet et al. J Neurology 55:1122-8, 2000). Late onset tends to present with progressive proximal muscle weakness and respiratory insufficiency (Winkel et al. J Neurology 252:875-84, 2005). We report two cases of biopsy confirmed adulto nset GSDII, along with key Magnetic Resonance (MR) images.