One hundred three consecutive patients undergoing 106 thoracotomies for primary lung carcinoma were reviewed to determine factors associated with the development of postoperative pulmonary complications. Pulmonary complications occurred in 40 of 104 (39 percent) patients. Minor complications occurred in 17 of 104 (16 percent) patients and major in 23 of 104 (22 percent). There were six deaths in the entire series of 103 patients (6 percent), two of which were directly caused by a pulmonary complication and one where it was a contributing factor. Extended surgical resections were associated with an increased risk of complications. Pulmonary complications occurred in 9 of 11 (82 percent) patients undergoing extended resections involving chest wall resection. The use of neoadjuvant chemotherapy also was associated with an increase in the rate of major complications. Poor nutritional status as measured by a history of weight loss and preoperative serum albumin levels also was associated with an increased risk of any pulmonary complication. Cardiac complications were significantly increased in the group of patients having pulmonary complications. Pulmonary complications continue to present a major source of morbidity and mortality for patients undergoing thoracotomy for lung carcinoma. Determination of factors associated with increased risk is important in order to identify patients who might be predisposed to the development of these complications.