Lung resection would be associated with lower jugular bulb oxygen saturation (SjvO₂) values in patients with moderate to severe pulmonary dysfunction. We aimed to study the effects of lung resections on the postoperative changes in SjvO₂, incidence of SjvO₂ < 50%, pulmonary functions, cerebral blood flow equivalent (CBFE), and arterial to jugular difference in oxygen content (AjvDO₂) in the patients with pulmonary dysfunction. Fifty-three patients scheduled for lung resection were allocated on the basis of forced vital capacity (FVC %) and forced expiratory volume in 1 second (FEV(1)%) into the following: good FVC and FEV₁ (n = 14), mild (n = 14), moderate (n = 13), and severe (n = 12) pulmonary dysfunction groups. After lung resections, patients with pulmonary dysfunctions had significantly lower SjvO₂, CBFE, FEV₁, and FVC (P < .001), higher AjvDO₂ (P < .001), and frequent episodes with SjvO₂ < 50% (P < .03). Perioperative changes in FEV₁ had a significant negative correlation with SjvO₂ desaturation (P < .002). Patients with pulmonary dysfunction showed significant SjvO₂ < 50% after lung resection, which is correlated to the perioperative changes in FEV₁.