Multiple sclerosis (MS) patients attending MS clinics located at the University of British Columbia Hospital, Winnipeg Health Sciences Centre, Dalhousie (Halifax, Nova Scotia) MS clinic, London Health Sciences Centre (London, ON) and Hôpital Notre-Dame (Montréal). Participants must have definite MS (Poser or McDonald criteria), with a relapsing-remitting or secondary-progressive disease course, registered at one of the above MS Clinics and prescribed a beta-interferon as an immunomodulatory drug for MS.