Deaths and death rates for mesothelioma of the pleura are presented by age, sex, and geographic area for the United States for the years 1968-81. Death rates increased with age and in every age group were roughly three times higher for males than for females. Over the period 1968-81, death rates increased for males aged 65 years or more, whereas death rates in other age-sex groupings remained fairly constant or declined slightly. It is known that asbestos is highly related to mesothelioma, and the increase in death rates among older males could be due to asbestos. Conversely, the fact that death rates in younger males and in females have not been increasing suggests some kind of background level not strongly related to the use of asbestos. When the geographic distribution of death rates was examined by state, there was considerable geographic variation with some clustering. High death rates for males appeared for the Northeastern States and along the Pacific Coast, and for Illinois, Florida, Wyoming, and Colorado. Females shared this geographic pattern to some extent. When death rates were examined by county, a relationship was seen between pleural mesothelioma deaths among males and the presence of asbestos products plants and shipbuilding facilities. Excessive death rates in some counties and states did not appear to be related to asbestos exposure. Although the similarity in geographic patterns of mortality for males and females suggests a common etiology, the trends in mortality suggest different etiologies. There may be important causes of pleural mesothelioma yet to be identified.