Although there is no evidence that electromagnetic energy in the radio frequency radiation (RFR) band is mutagenic, there have been suggestions that RFR energy might serve as either a promoter or co-promoter in some animal models of carcinogenesis. Recent developments in electromagnetic technology have resulted in the manufacture of RFR sources capable of generating frequencies in the millimeter wavelength (MMW) range (30-300 GHz). Because absorption of MMW energy occurs in the skin, it is to be expected that long-term detrimental health effects, if any, would most likely be manifest in the skin. In this study we investigated whether a single (1.0 W/cm(2) for 10 s) or repeated (2 exposures/week for 12 weeks, 333 mW/cm(2) for 10 s) exposure to 94 GHz RFR serves as a promoter or co-promoter in the 7,12-dimethylbenz[a]anthracene (DMBA)-induced SENCAR mouse model of skin carcinogenesis. Neither paradigm of MMW exposure significantly affected papilloma development, as evidenced by a lack of effect on tumor incidence and multiplicity. There was also no evidence that MMW exposure served as a co-promoter in DMBA-induced animals repeatedly treated with 12-O-tetradecanoylphorbol 13-acetate. Therefore, we conclude that exposure to 94 GHz RFR under these conditions does not promote or co-promote papilloma development in this animal model of skin carcinogenesis.