Postoperative morbidity and mortality were correlated with the preoperative results of three widely used pulmonary function tests (FVC, FEV1, FEV1/FVC) in 100 consecutive patients who underwent pneumonectomy for lung carcinoma. Factor analyzed following operation included thirty-day mortality, incidence of cardiovascular and respiratory complications, number of individuals requiring prolonged mechanical ventilation. Nineteen patients had a forced vital capacity (FVC) of 70% or less of the normal value, seven had a one-second forced expiratory volume (FEV1) of 1.5 liters or less, and thirty-three had a FEV1 of less than 2 liters. Fourteen patients had a FEV1/FVC ratio of 65% or less. There were no differences in morbidity or mortality between these patients and those presenting higher test scores. As a general rule, decisions regarding operability and extent of resection cannot be made solely on the basis of the three spirometry tests reviewed.