Postoperative pulmonary complications are often fatal in patients with oesophageal cancer. The influence of various preoperative and perioperative risk factors in the prediction of such complications was analysed. Some 170 oesophageal resections performed through a thoracotomy between January 1977 and December 1991 were reviewed. Twenty-two parameters generated from various medical risk categories were studied. Six variables were significant (P < 0.05) on univariate analysis: vital capacity, serum albumin level, partial pressure of carbon dioxide in arterial blood, presence of liver cirrhosis, presence of chronic obstructive airway disease and clinical stage of the tumour. Multivariate discriminant analysis of these six factors identified three as significant, namely vital capacity (P < 0.0001), liver cirrhosis (P = 0.01) and tumour stage (P = 0.01), yielding an equation for assessment of the risk of postoperative pulmonary complications. Calculation of the risk score showed that 42 of 53 patients with pulmonary complications had scores of 0 or more and that 74 of 102 without had scores below 0. The mean risk score was 0.34 for patients with complications and -0.26 for those without. The equation predicted pulmonary complications after transthoracic oesophagectomy with 74.8 per cent accuracy, 79.2 per cent sensitivity and 72.5 per cent specificity. It is concluded that the risk of postoperative pulmonary complications can be accurately assessed in individual patients by calculation of a risk score based on vital capacity, liver cirrhosis and tumour stage.