Objectives: A protective inferior vena cava (IVC) filter may later be incorporated into a chronic postthrombotic ilio-caval obstruction (occlusive, requiring recanalization, or nonocclusive). This study aims to assess the safety and stent-related outcome following stenting across an obstructed filter. Methods: From 1997 to 2009, 708 limbs had stenting for postthrombotic ilio-caval outflow obstruction (occlusion in 121 limbs). In 25 patients, an IVC filter was obstructed (Group X). The site was crossed by a guidewire and balloon dilated. The filter was markedly displaced sidewise or remodeled. A stent was placed across the IVC filter and redilated. In 28 other patients, the cephalad stenting terminated below a patent IVC filter (Group B). The remaining 655 patients had no previous IVC filter placement (Group no IVC filter present [NF]). The patients were followed to assess patency. The types of reintervention were noted. Results: The stenting maneuver through a variety of previously inserted IVC filters was safely performed without an apparent tear of the IVC, no clinical bleeding or abdominal symptoms, or pulmonary embolism. Mortality was nil; morbidity minimal. The primary and secondary cumulative patency rates at 54 months for limbs with postthrombotic obstruction were with and without IVC filter (38% and 40%; P =.1701 and 79% and 86%; P =.1947, respectively), and for limbs with stenting across the filter (Group X) and stent termination below the filter (Group B; 32% and 42%; P =.3064 and 75% and 84%; P =.2788, respectively), not statistically different. When Group X alone was compared with Group NF, the secondary patency rate was, however, significantly lower (75% vs 86%; P =.0453), suggesting that crossing of the stent was associated with reduced patency. Occlusive postthrombotic disease requiring recanalization was more frequent in Group X than in Group B and Group NF (68%, 25%, and 15%, respectively; P =.004). A comparison was therefore performed only between limbs stented for recanalized occlusions with (n = 23) and without IVC filters (n = 92) showing no difference (cumulative primary and secondary patency rates 30% and 35%; P =.9678 and 71% and 73%; P =.9319, respectively). Multiple logistic regression analysis also supported a significant association between patency rate and occlusive disease (odds ratio, 6.9; 95% confidence interval, 3.4-13.9; P <.0001), but not between patency rate and presence of an IVC filter (P =.5552). Conclusions: Stenting across an obstructed IVC filter is safe. It appears that patency is not influenced by the fact that an IVC filter is crossed by a stent, but is related to the severity of postthrombotic disease (occlusive or nonocclusive obstruction) and the associated recanalization procedure. © 2011 Society for Vascular Surgery.