This paper reviews the aetiology, distribution and projected future incidence of malignant mesothelioma. Asbestos exposure is the most thoroughly established risk factor. Debate continues regarding the relative importance of the different asbestos fibre types and the contribution of Simian virus 40 (SV40). Disease incidence varies markedly within and between countries. The highest annual rates of disease, approximately 30 case per million, are reported in Australia and Great Britain. The risk of disease increases with age and is higher in men. Time from asbestos exposure to disease diagnosis is on average greater than 40 years. Non-occupational asbestos exposures contribute an increasing proportion of disease. With the exception of the United States, incidence continues to increase. In developed countries peak incidence is expected to occur before 2030.