There is sufficient evidence that anesthetics may cause cancer to justify a test of their carcinogenic potential. Baden, et al., using the Ames test, a rapid and inexpensive genetic indicator of carcinogenicity, have shown that among currently used anesthetics fluroxene alone caused bacterial mutations. The authors used the sister chromatid exchange (SCE) technique, another rapid assay of mutagenic-carcinogenic potential. The frequency of sister chromatid exchanges in Chinese hamster ovary cells increases when the cell cultures are exposed to mutagen-carcinogens, particularly in the presence of a metabolic activating system. With this test system a one-hour exposure to 1 MAC nitrous oxide, diethyl ether, trichloroethylene, halothane, enflurane, isoflurane, methoxyflurane, or chloroform did not increase SCE values. Divinyl ether, fluroxene and ethyl vinyl ether increased SCE values in the same circumstances. Results of this study of mammalian cells suggest that no currently used anesthetic is a mutagen-carcinogen. The results also suggest that anesthetics containing a vinyl moiety may be mutagen-carcinogens.