Alglucosidose alpha has been developed for the treatment of Pompe disease, a rare, progressive, and often fatal muscular disease caused by deficient activity of the lysosomal enzyme alphaglucosidase. Clinical data from the clinical trials show that the enzyme replacement therapy significantly prolongs survival in infants, clears glycogen from cardiac muscle and improves cardiac and skeletal muscle function. Skeletal muscle response is variable, the best results are noted in patients treated early, prior to severe skeletal muscle damage. However there are patients who have not a good response despite early treatment. More distance is needed to establish the possible role of different other factors in determining outcome and the extent of long-term benefit. Trials of enzyme replacement therapy in late onset Pompe disease are underway The availability of this therapeutic option makes early identification of this condition even more critical.