The Mucopolysaccharidosis I (MPS I) Registry is an ongoing, observational database that tracks the outcomes of patients with MPS I. The data collected by the MPS I Registry will provide information to better characterize the natural history and progression of MPS I as well as the clinical responses of patients receiving enzyme replacement therapy, such as Aldurazyme (Recombinant Human Alpha-L-Iduronidase), or other treatment modalities.