Patients with MPS II often present with limitations to functional mobility. With the advent of enzyme replacement therapy (ERT), robust assessment tools are important to assess response to treatment. The aim of this study was to see if the GAITRite™ system (electronic pressure sensitive walkway) could identify any changes to gait pattern following commencement of ERT. Six boys with MPS type II were assessed at baseline and at intervals post commencing ERT. Four individual characteristics of gait were studied - velocity, cadence, step length and base of support. Changes in parameters for each individual could be analysed and be compared with age matched controls. The data generated from the GAITRite™ indicated all six boys had changes to their gait pattern. The most notable changes were in velocity, step length and base of support. The GAITRite™ was found to identify changes in gait parameters in this group of patients. It is an accessible way of providing both quantitative and qualitative analysis of gait in the clinical environment, and could potentially be used to monitor response to treatment. Larger studies are needed to corroborate our findings, as well as to establish the GAITRite™ as a monitoring tool.