A critical review of close to 100 published and unpublished but otherwise available epidemiologic reports of petroleum industry employees from the United States, United Kingdom, Canada, Europe, Australia, and Japan was conducted. Analyses by duration of employment and latency are discussed, and summary standardized mortality ratios (SMRs) or meta-SMRs are developed for selected cancer sites. Findings indicate that the industry experienced a significantly lower cancer mortality than the general population for all cancer sites combined, digestive system, stomach, and lung. For the industry as a whole, SMRs similar to the general population were observed for skin, brain, pancreatic, prostatic, and kidney cancers. However, some data indicate that certain small groups within the industry might have elevated prostatic and kidney cancer risk. This review supports the conclusion that some refinery employees, particularly those employed before the 1940s, may have been at increased risk of leukemia. There is some indication that cancer of other lymphatic tissue may also be elevated. Unresolved issues affecting these conclusions are discussed, and specific directions for future research are offered.