Although enzyme replacement therapy (ERT) has become an alternative for treating Hunter's syndrome (MPS II) in the last 10 years, evidence on its efficacy and safety is limited. This review analyzed 22 studies on ERT for MPS II. It found that ERT significantly improved 6-minute walk tests, vital lung capacity, left ventricular mass index and ejection fraction. ERT also showed benefits for urinary glycosaminoglycans, spleen and liver size, quality of life and articular mobility, but less clear effects on growth, cognitive impairment and sleep apnea. Adverse effects occurred in 7-8% of patients and were not related to antibodies, usually appearing in the first 3 months. One study found home