Patients with gliomas of the central nervous system hospitalized during the period January 1979--March 1980 at the Neurological Institute C. Besta of Milan were compared with controls admitted to the Institute in the same period for nonneoplastic neurologic diseases or benign tumors. The comparison was based on occupational history, smoking habits, and alcohol consumption. Two analyses were carried out: the first by case-control pairs matched for age, sex, and residence; the second by age, sex, and residence stratification. Patients with glioma were more likely than controls to have worked in agricultural activities and showed a relative risk of 5.0 (p = 0.043) in the matched analysis and 1.9 (p = 0.113) in the analysis by stratification. This high risk was confined to those who performed agricultural work after 1960, suggesting a possible etiologic role of exposure to organic pesticides, fertilizers, and herbicides, which have only recently been commonly used in Italy. No significant difference was observed between cases and controls in regard to other analyzed occupations and habits.