This is a single center, open-label study of patients with late infantile MLD. All patients were previous treated 26 weeks in the phase I trial (EudraCT number: 2006-005341-11). All patients will be offered continuing treatment in this study and will in this protocol receive 13 infusions, whereby the patients total have had 27 infusions of Metazym. One infusion will be given every other week. After a total of 52 weeks of treatment the subjects will continue treatment in a compassionate use protocol. Safety (AE/SAE) will be monitored at every visit. The efficacy observed during the first 26 weeks of treatment in the phase I trial (EudraCT number: 2006-005341-11) will be studied further during totally 1 year of treatment. The myelin recovery (CNS and PNS) and functional capacity will be evaluated after this long-term treatment.

Inclusion Criteria:

• Subject's legally authorized guardian(s) must provide signed, informed consent prior to performing any study-related activities (trial-related activities are any procedures that would not have been performed during normal management of the subject)
• The subject and his/her guardian(s) must have the ability to comply with the clinical protocol

Exclusion Criteria:

• Spasticity so severe to inhibit transportation
• Presence of known clinically significant cardiovascular, hepatic, pulmonary or renal disease or other medical condition that, in the opinion of the Investigator, would preclude participation in the trial
• Any other medical condition or serious intercurrent illness, or extenuating circumstance that, in the opinion of the Investigator, would preclude participation in the trial
• Use of any investigational product other than rhASA within 30 days prior to study enrolment or currently enrolled in another study which involves clinical investigations