In a prospective study of 13 patients requiring pneumonectomy for unilateral post-tuberculous lung destruction the left side was found to be affected in 12. Review of a further 172 cases showed the left lung to have been destroyed in 109 (63%). It is suggested that this predominance of the left side is due to the anatomical characteristics of the left main bronchus and that disordered haemodynamics also appear to play a part.Unilateral total post-tuberculous lung destruction is a well recognised cause ofmorbidity and mortality.' 2 In Saudi Arabia late presentation and poor compliance with treatment for tuberculosis (as low as 30%') account for an appreciable number of patients presenting in this way, but very few studies have dealt with the problem in detail.4 We report the clinicopathological and haemodynamic findings in 13 patients coming to surgery at King Khalid University Hospital. The left lung was affected more frequently than the right, and we discuss the reasons for this predilection. Patients and methodsWe studied 13 patients with unilateral lung destruction before elective pneumonectomy, by bronchoscopy, bronchography, pulmonary angiography, thoracic aortography, ven-