Glycogen storage disease type II (GSD-II), also known as Pompe disease, is a rare autosomial recessive disease due to deficiency of lysosomal acid alpha-glucosidase (GAA). The infantile-onset form is the most severe, and most patients present with hypotonia and cardiomyopathy in early infancy. We report on a typical case of Pompe disease in a patient who died at 8 months of age due to aspiration pneumonia and hypertrophic cardiomyopathy. Genetic studies showed deficient GAA activity and mutation of the GAA gene with Gly615Arg (exon 13, G1845A). On autopsy, glycogen had markedly accumulated in the liver, myocardium and skeletal muscle. The neurons of the anterior horn of the spinal cord and medulla were also involved, but the cortex was spared. These neurological-histologic findings may explain the clinical features of poor motor function, decreased deep tendon reflexes and lack of mental retardation.