Asbestos exposure constitutes the primary cause of pleural and peritoneal mesothelioma in humans. Risk relates to the duration and intensity of exposure. Thus, those exposed at younger ages are at higher lifetime risk. Families of asbestos workers exposed to asbestos on hair and clothing as well as to asbestos items brought home from the workplace are also at risk, as are employees working in the same vicinity as asbestos workers. The public health significance of exposure from asbestos in public and private buildings remains controversial. Malignant mesothelioma is difficult to diagnose and carries a poor prognosis. Chemotherapy with single or multiple agents has thus far been disappointing, but doxorubicin and cisplatin or mitomycin and cisplatin are probably most active with response rates in measurable disease of 25%. Palliative radiotherapy is also problematic since differences between tumor cytotoxicity and pulmonary tolerance are small and radiation pneumonitis may significantly impair quality of life.