The potential genotoxic effects of chronic exposure to radiofrequencies used for mobile communication were investigated in a rodent study by determining the incidence of micronuclei in peripheral blood erythrocytes. Male and female B6C3F1 mice were exposed to RF signals of the Global System for Mobile Communications (GSM, 902 MHz) or Digital Cellular System (DCS, 1747 MHz) for 2 hours/day, 5 days/week for two years at maximal body-averaged absorption rates of 0.4, 1.3 and 4.0 W/kg body weight. There were no significant differences in the frequency of micronuclei compared to sham-exposed mice and cage controls, while a significant increase was observed in erythrocytes of positive control mice injected with mitomycin C. In conclusion, the study did not provide any evidence of RF-induced genotoxicity in mice after two years of exposure.