Non malignant asbestos diseases are dominated numerically by pleural plaques. This form of circumscribed fibrosis of the parietal pleural is generally asymptomatic and its potential for evolution is weak. More rarely diffuse pleural fibrosis results from disease of the visceral pleura with a secondary fusion of the two pleural layers. Usually it follows a pleural effusion which resolves spontaneously. Its functional effects are sometimes important. The generalised practice of computerized tomographic scanning as a work up for asbestos related disease has revealed the frequent association of this diffuse pleural fibrosis with a particular form of peripheral pulmonary collapse called round atelectasis. Asbestosis or pulmonary fibrosis induced by the inhalation of asbestos has become rarer due to the improvement in working conditions in the asbestos industry. It develops following heavy exposure. The frequency of bronchopulmonary cancer is increased when asbestosis exists although it is not currently possible to say if the two disorders are independent and each is only conditioned by exposure to asbestos or if the two diseases are inextricably linked by the same physiopathological process.