Disclosed is the use of an arylsulfatase A (ASA) protein in the manufacture of a formulation for the treatment of metachromatic leukodystrophy (MLD), wherein treatment includes intrathecal administration of the formulation to a subject in need of treatment, wherein the formulation comprises an arylsulfatase A (ASA) protein at a concentration at or greater than about 5 mg/ml, and wherein the formulation comprises no greater than 50 mM of phosphate, and a polysorbate.