BACKGROUND: Many Canadians with multiple sclerosis (MS) have recently travelled internationally to have procedures for a putative condition called chronic cerebrospinal venous insufficiency (CCSVI). Here, we describe where and when they went and describe the baseline characteristics of persons with MS who participated in this non-evidence-based medical tourism for CCSVI procedures. METHODS: We conducted a longitudinal observational study that used online questionnaires to collect patient-reported information about the safety, experiences, and outcomes following procedures for CCSVI. A convenience sample of all Albertans with MS was recruited between July 2011 and March 2013. RESULTS: In total, 868 individuals enrolled; 704 were included in this cross-sectional, baseline analysis. Of these, 128 (18.2%) participants retrospectively reported having procedures for CCSVI between April 2010 and September 2012. The proportion of participants reporting CCSVI procedures declined from 80 (62.5%) in 2010, to 40 (31.1%) in 2011, and 8 (6.3%) in 2012. In multivariable logistic regression analysis, CCSVI procedures were independently associated with longer disease duration, secondary progressive clinical course, and greater disability status. CONCLUSIONS: Although all types of people with MS pursued procedures for CCSVI, a major driver of participation was greater disability. This highlights that those with the greatest disability are the most vulnerable to unproven experimental procedures. Participation in CCSVI procedures waned over time possibly reflecting unmet expectations of treated patients, decreased media attention, or that individuals who wanted procedures had them soon after the CCSVI hypothesis was widely publicized.