Muslin wrapping is a commonly utilized alternative technique in the treatment of aneurysms that are not amenable to direct clipping. In this case report, we describe two patients from different institutions who both required aneurysm wrapping with gauze/muslin for aneurysm reinforcement. Both patients developed an inflammatory foreign body response to muslin visible on MRI that resulted in a vasculitic stenosis. The onset of TIAs was at 6 months and 1 month postoperatively, respectively. The stenoses rapidly progressed to near occlusion despite antiplatelet therapy, and in one case, an aggressive corticosteroid regimen. One patient eventually developed leptomeningeal collateral flow that allowed tolerance of the stenosis, while the other patient required microsurgical bypass. These cases reports are the first to our knowledge that describe the adverse effects of muslin wrapping without adhesive reinforcement, as well as one of few reports to include follow-up angiographic imaging.