Positron emission tomography (PET) can be used to evaluate pulmonary vascular endothelial permeability by measuring the pulmonary transcapillary escape rate (PTCER) for radiolabeled transferrin. Because epithelial permeability, as evaluated by other techniques, is significantly affected by cigarette smoking, we used PET to compare the effects of smoking on extravascular lung density (EVD) and PTCER in seven normal chronic cigarette smokers within 30 min of smoking a cigarette and seven normal nonsmokers. We found no difference in PTCER and EVD between the two groups. We conclude that the interpretation of acute or chronic lung injury studies with PET should not be affected by cigarette smoking in the subject population.