The incidence of peri-operative pulmonary complications varies, depending on surgery and patient related determinants. Risk factors include upper abdominal or thoracic surgery, duration of anaesthesia, age, obesity, smoking history and underlying respiratory diseases such as COPD. The preoperative evaluation of patients undergoing general surgery is predominantly based on medical history and physical examination. A preoperative chest radiograph and pulmonary function tests are indicated in some high risk patient groups, and in all patients about to undergo lung resection surgery. If in this latter group, the preoperative lung function is severely compromised, a quantitative perfusion scan and exercise testing may be useful for the assessment of the operative risk. Prevention of postoperative pulmonary complications should begin with discontinuation of smoking at least 8 weeks prior to surgery. In high risk patients preoperative chest physiotherapy, including incentive spirometry, is clearly beneficial.