Endotoxin prepared from Enterobacter agglomerans isolated from cotton dust was aerosolized and evaluated using a mouse inhalation model. C57 BL/6J mice were injected in a lateral tail vein with Lewis lung carcinoma (LL/2), exposed to aerosolized endotoxin and treated for two and a half hours a day, five days a week. The results indicate that the inhaled endotoxin reduces lung cancer involvement in treated mice as compared with control animals. The anti-cancer activity of inhaled E. aqqlomerans endotoxin is similar to that produced by aerosolized Escherichia coli. These results support epidemiological evidence that endotoxin in aerosolized cotton dust inhibits lung cancer.