Inclusion Criteria

• Patient consent
• Patient must be seven years of age or older
• Patient must have documented biochemical or genetic proof of MPS VI
• The patient must be able to walk independently at least 5 meters and no more than 270 meters in the first 6 minutes, or no more then 400 meters total in 12 minutes, in the screening 12-minute walk test
• If female of childbearing potential, patient must have a negative pregnancy test

Exclusion Criteria

• Patient is under consideration for or has undergone a successful bone marrow transplant (BMT)
• Patient refuses or is unable to complete all screening evaluations
• Pregnant or lactating patient
• Patient has received an investigational drug within 30 days prior to study enrollment
• Patient has been previously treated with rhASB
• Patient has a medical condition, serious intercurrent illness, or other extenuating circumstance that may significantly confound study results or decrease study compliance
• The patient has clinically significant spinal cord compression
• The patient has known hypersensitivity to rhASB or to components of the active or placebo test solution