(1) Pompe disease is the early-onset form of type 2 glycogenosis, a rare enzyme deficiency. Onset occurs in early infancy, and most patients die from cardiorespiratory failure before their first birthday. (2) The missing enzyme, alglucosidase alfa is now produced through biotechnology and is approved as replacement therapy for infants with Pompe disease. (3) According to a dose-finding study involving 19 infants, and a somewhat shaky historical comparison, alglucosidase alfa has a positive impact on survival at the age of 18 months. (4) The main known adverse effects of alglucosidase alfa are potentially severe infusion reactions and the development of anti-alglucosidase antibodies. (5) Treatment requires an intravenous infusion every two weeks. In France, it costs 4200 euros for a child weighing 10 kg. (6) Alglucosidase alfa replacement therapy is the only treatment that seems to improve the short-term survival of infants with Pompe disease. However, it should only be used within a context of continued assessment.