Benzene is a widely distributed environmental contaminant known to cause acute myeloid leukemia, aplastic anemia, and perhaps other hematopoietic neoplasms, related hematopoietic disorders, and possibly other cancers. In a binational, multidisciplinary effort, investigators from NCI and the Chinese Centers for Disease Control (CDC) have conducted a follow-up investigation during 1972 to 1987 of approximately 75,000 Chinese benzene-exposed workers and 35,000 unexposed workers from more than 700 factories in 12 cities. Investigators found that workers exposed to benzene were at significantly higher risk of developing acute myeloid leukemia, myelodysplastic syndromes, and non-Hodgkin lymphoma. Risk varied by temporal patterns of exposure with recent exposure mostly strongly linked with acute myeloid leukemia and myelodysplastic syndrome, whereas distant exposure was more strongly associated with non-Hodgkin lymphoma. In parallel cross-sectional investigations carried out in Shanghai during 1992 and Tianjin during 2001, NCI and CDC collaborators have made steady progress in elucidating the mechanisms of benzene-induced carcinogenesis, biomarkers of benzene’s early effects, and identifying genetic markers of susceptibility. Currently, a case-cohort study is in progress that extends the follow-up through 1999 and will quantify benzene-related dose-response in relation to hematopoietic malignancies and related disorders, benzene hematotoxicity, and lung cancer. Molecular and genetic studies are underway to assess potential genetic susceptibility in relation to development of benzene hematotoxicity.