The effects of exposure to 1,3-butadiene (106990) and styrene (100425) in the synthetic rubber manufacturing industry on the risks of lymphohematopoietic cancers (LHCs) were examined. There were 58 LHC cases identified from an original cohort of 12,110 synthetic rubber workers employed at eight factories. Diagnostic information was obtained from hospital records and death certificates. The controls consisted of 1,242 synthetic rubber workers included in a larger case/control study of several cancer sites. Butadiene and styrene exposure data were supplied by NIOSH. The risks of leukemia and Hodgkin's disease were significantly elevated among workers with an average working lifetime butadiene exposure level of 1 part per million (ppm), with odds ratios (ORs) of 1.50 and 1.73, respectively. The risks of all LHC, all lymphomas, lymphosarcoma, and myeloma were significantly elevated among workers with an average working lifetime styrene exposure level of 1ppm, with ORs of 2.20, 2.67, 3.88, and 3.04, respectively. Cumulative exposure levels were also related to LHC incidence. Work duration in the synthetic rubber industry had a significant influence on the incidence of LHCs. The risk of leukemia was significantly elevated among workers with a long duration of work in the service, labor, or laboratory departments, with ORs of 2.64 for all leukemias and 3.70 for myeloid leukemias. Lymphoid leukemias were not associated with the work area variable. The authors conclude that the occurrences of LHCs in this cohort are associated with industrial exposures to either butadiene or styrene.