The association between occupational and other environmental exposures was evaluated in 60 acute myelogenous leukemia cases and controls. Odds ratios and 95% confidence intervals for prior cytotoxic therapy and benzene exposure, adjusted for age, sex, and race by logistic regression, were 3.7 (0.7, 19.9) and 2.6 (0.4, 15.2), respectively. No other work-related associations, including employment in electrical occupations, were present. Other associations were suggestive but may have been due to biases in control selection or small numbers of subjects. The risks for prior cytotoxic therapy (odds ratio = 10.2) and benzene exposure (odds ratio = 11.4) were concentrated in 13 patients with French-American-British M4 leukemia; no environmental exposures were associated with French-American-British subtypes M1 and M2. These findings support the concept that French-American-British histological subtypes of AML may have different etiologies.