<jats:sec> <jats:title>Background and Purpose—</jats:title> <jats:p>After pneumonectomy or lobectomy, at least 1 blind pulmonary vein is left with potential risk of postoperative thromboembolic incidents. We investigated the risk of stroke within this population compared with background and pulmonary wedge resections controls.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods—</jats:title> <jats:p>We identified 12 965 patients with pneumonectomy or lobectomy and 6400 patients with wedge resection using data from Danish nationwide registries from 1996 to 2016. In multivariate Poisson regression analysis, we estimated incidence rate ratios of stroke for patients undergoing lobectomy or pneumonectomy versus background population controls and patients who underwent wedge resection. We stratified our analysis by days: 0 to 30, 31 to 90, 91 to 180, and 180 to 365 after surgery and performed a subgroup analysis in patients with lung cancer.</jats:p> </jats:sec> <jats:sec> <jats:title>Results—</jats:title> <jats:p>The incidence rate of stroke was 10.6 per 1000 person-years for time exposed for pneumonectomy or lobectomy and 2.3 per 1000 person-years for patients not exposed for pneumonectomy or lobectomy. In the 0- to 30-day multivariate Poisson regression analysis, compared with the background population, pneumonectomy or lobectomy was associated with an increased risk of stroke both patients with and without atrial fibrillation (incidence rate ratios [IRR]) of 4.66 (95% CI, 2.04–7.12) and 5.43 (95% CI, 3.99–7.41), respectively. Similarly, in patients with lung cancer, the first 30 days after pneumonectomy or lobectomy remained a risk factor for stroke for patients with (IRR, 2.94; 95% CI, 1.39–6.25) and for patients without atrial fibrillation (IRR, 2.56; 95% CI, 1.86–3.59).When compared with wedge resection, 0 to 30 days after lobectomy or pneumonectomy was also associated with increased risk of stroke (IRR, 2.63; 95% CI, 1.19–5.81); however, this association was insignificant in patients with lung cancer (IRR, 2.98; 95% CI, 0.72–12.29).</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions—</jats:title> <jats:p>Patients undergoing pneumonectomy or lobectomy had an increased 30 days risk of stroke. Whether the pulmonary vein stump is a risk factor for stroke and whether preventive strategies are relevant require further investigation.</jats:p> </jats:sec>