A survey of cancer mortality from 1950 to 1969 was conducted in U.S. counties where the petroleum industry is most heavily concentrated. Male residents of these counties experienced significantly higher rates for cancers of the lung, the nasal cavity and sinuses, and the skin (including malignant melanoma) compared to male residents of counties with similar demographic characteristics. Further study is needed to determine whether these patterns result from exposure to chemical carcinogens, including polycyclic hydrocarbons, involved in the manufacturing of petroleum.