Background: Laronidase (Aldurazyme^®) is a recombinant formulation of α-L-iduronidase, the enzyme deficient in mucopolysaccharidosis type I (MPS-I); a disorder associated with skeletal dysplasia, restricted joint movement, short stature, obstructive pulmonary disease, cardiac valvular problems and cognitive impairment (in the severe and intermediate variants). Objective: To describe MPS-I and review data on the safety and efficacy of laronidase. Results: Laronidase is safe and effective in stabilizing or improving pulmonary function and physical endurance. As intravenously administered enzyme is unable to correct CNS disease, hematopoietic stem cell transplantation remains the primary treatment for Hurler's syndrome despite the morbidity and mortality risks. Conclusions: Palliative care remains part of the treatment. Long-term studies are required to ascertain the effect of enzyme therapy on survival and its effectiveness in modifying the disease course and reducing morbidity. Intrathecal administration is under investigation for patients with signs of cord compression secondary to glycosaminoglycan accumulation within the dura matter. The cost of therapy remains a concern.