The prediction of postoperative pulmonary complications is an underinvestigated field. We conducted a prospective cohort study (with postoperative pulmonary complications ascertained by an investigator blinded to perioperative variables) to determine the risk factors for pulmonary complications after elective nonthoracic surgery. Of 1,055 consecutive patients attending the Pre-Admission Clinic of a university hospital (mean age 55 years, 50% men, 15% with history of obstructive airways disease), 28 (2.7%) suffered a postoperative pulmonary complication within 7 days of surgery: 13 patients developed respiratory failure requiring ventilatory support, 9 pneumonia, 5 atelectasis requiring bronchoscopic intervention, and 1 pneumothorax requiring intervention. Mean lengths of stay were substantially prolonged for those patients who developed pulmonary complications within 7 days of surgery: 27.9 days versus 4.5 days, p = 0.006. Eight variables were statistically significantly associated with pulmonary complications on bivariate analyses. Multivariate analyses revealed that four were independently associated with increased risk of pulmonary complications: age (odds ratio [OR] 5.9 for age >/= 65 years, p < 0.001), positive cough test (OR 3.8, P = 0.01), perioperative nasogastric tube (OR 7.7, p < 0.001), and duration of anesthesia (OR 3.3 for operations lasting at least 2.5 hours, p = 0.008). Thus, several perioperative factors predict an increased risk for pulmonary complications after elective nonthoracic surgery.