We performed a case-control study on astrocytomas to test previous hypotheses and to generate new ones. The study groups consisted of 78 cases, 197 clinical controls, and 92 population controls. Comparisons with both groups of controls showed an excess risk for persons who had lived in the vicinity of a farm. The risk for persons exposed to herbicides or insecticides was elevated, although less so compared with the population controls. Frequent intake of smoked food was associated with an excess risk compared with the population controls but not when compared with the clinical controls.