Chronic cerebrospinal venous insufficiency (CCSVI) is a hypothesis through which cerebral venous drainage abnormalities contribute towards the pathogenesis of multiple sclerosis. CCSVI venoplasty is already practised worldwide. We report the case of a 33-year-old lady with multiple sclerosis who underwent left internal jugular venoplasty resulting in iatrogenic jugular thrombosis requiring open thrombectomy for symptom relief. This occurred without insertion of a stent and while fully anticoagulated. Clinicians should be aware that endovenous treatment of CCSVI could cause paradoxical deterioration of cerebral venous drainage. Patients with complications post venoplasty are now presenting to geographically distant vascular units.