The present invention relates to the intrathecal (IT) administration ofrecombinant enzyme to treat lysosomal storage disorders. In an exemplaryembodiment, intrathecal administration of human .alpha.-L-iduronidase (rhIDU)injections in MPS I affected animals resulted in significant enzyme uptake,significant rh-iduronidase activity in brain and meninges and a decrease ofglycosaminoglycan (GAG) storage in cells of MPS I subjects to that of normalsubjects. Intrathecal administration proved more effective than intravenoustreatment at alleviating MPS I symptoms, indicating it is a useful method oftreating lysosomal storage disorders.
