Objectives: Diesel engine exhaust (DE) accounts for a significant percentage of air pollutants that are associated with various health outcomes including mortality, asthma, chronic bronchitis, respiratory tract infection, etc. In June, 2012, the International Agency for Research on Cancer (IARC) released the assessment results that classified DE as "carcinogenic to humans" (Group 1). This review is therefore focused on the lung cancer risks of DE. Methods: Literatures were searched using PubMed with key words of "diesel exhaust", "lung cancer", and other related terms for the period between 1990 and 2012. A total of 295 articles were searched and sixteen epidemiologic studies were identified as potentially relevant. Results: Sixteen epidemiologic studies about the lung cancer risks of workers exposed to DE in various occupations were summarized in two tables, 1) retrospective cohort studies and 2) case-control studies. Increased lung cancer risk, although not always smoking adjusted, was observed in 6 out of 8 retrospective cohort studies and 4 of 8 case-control studies. Conclusions: Diesel fuel is widely used in Korea. Exposure to DE is confirmed to be a human carcinogen by IARC. Noncancer health risks of DE also need careful attention as DE is a major source of fine-particle pollution. Along with the efforts for reducing the DE emission through improvements of diesel engines and fuel, and the use of alternative fuels, comprehensive health risk assessment of DE should be conducted to minimize the adverse health effects.