Major alteration in respiratory mechanics occur in all patients following anaesthesia and thoracotomy because of a decrease in the functional residual capacity with minimal change in the closing volume leading to airway closure during tidal breathing and atelectasis. Diminished pulmonary reserve, because of non-pulmonary and pulmonary risk factors before operation, and/or restrictive ventilation and abnormal pattern of breathing due to postoperative pain sustain and aggravate these changes. These can proceed to postoperative pulmonary complications in some normal, and in many high risk, patients. Detection and correction of pre-existing pulmonary disease, smoking, sepsis and obesity is essential to reduce postoperative morbidity and mortality. Effective postoperative regional analgesia minimizes impairment of pulmonary function, aids in its recovery, and prevents postoperative pulmonary complications. The adjuvant use of chest physiotherapy and incentive spirometry should also help in decreasing the adverse affects of anaesthesia and surgery on the chest and thereby reduce the frequency and severity of postoperative complications.