This is a prospective cohort study to determine the effect of smoking cessation less than 8 weeks before elective surgery on the incidence of postoperative pulmonary complications (POPC). Subjects consisted of 237 adult patients who had smoked at least one cigarette within 8 weeks of their scheduled operation. They were observed up to 7 days post-surgery for development of atelectasis, tracheobronchitis, pneumonia, respiratory failure or bronchospasm. Fifty or 21.1% of the 237 patients had POPC during the observation period. Patients who quit smoking less than 2 weeks had a complication rate of 16.6%; while those who stopped between 2-4 weeks and 4-8 weeks before surgery had complication rates of 33% (OR 2.52; [1.11, 5.72]) and 25% (OR 1.68; [0.80, 3.55]), respectively. After adjusting for the effect of other risk factors, however, the impact of different intervals of smoking cessation on POPC was no longer apparent. In contrast, American Society of Anesthesiologists (ASA) status and chronic lung disease were found to be independent predictors of POPC. It was concluded that pre-operative smoking cessation less than 8 weeks neither reduced nor increased POPC and that any observed increase in POPC may be related to poorer medical condition, with sicker patients likely to undergo longer periods of abstention to reduce the risk of pulmonary complications.