Mouse embryo fibroblast cultures were pretreated with a variety of chemicals found in the environment. After chemical treatment, polyriboinosinic-polyribocytidylic acid was added to the cultures to induce alpha/beta interferon. Pretreatment of the cell cultures with the chemical carcinogens chloroform and beta-propiolactone severely inhibited the production of alpha/beta interferon, while pretreatment of the cell cultures with their poorly or noncarcinogenic analogs 1,1,1-trichloroethane and gamma-butyrolactone had no effect on interferon induction. Pretreatment of the cell cultures with the possible carcinogen diethylstilbestrol had no effect on alpha/beta interferon induction. Pretreatment of the cells with the poor or noncarcinogens pyrene and ascorbic acid did not effect interferon induction; in fact, treatment with ascorbic acid may have enhanced interferon production. These results augment previous findings that most potent carcinogens can inhibit the induction of alpha/beta interferon.