Whether or not ELF-MF has genotoxic potential is a controversial issue. In the present study, we investigated the genotoxic effect using cytogenetic assays (CA - SCE - MN), in 109 workers exposed to ELF-MF. The mean value of occupational exposure in the whole group was 0.35 microT. According to the exposure level the workers were stratified in two different groups: low exposed (n. 39, TWA < or = 0.2 microT) and higher exposed (n. 70; TWA > 0.2 microT): the groups did not significantly differ for the examined variables. Due to these results we decided to re-evaluate the effect only considering the highest exposed workers: we selected 31 workers exposed to TWA levels exceeding 1 microT, and compared vs. the low exposed subjects: again, the difference in the groups examined were not significant. At multivariate regression analysis was also applied: no correlation was observed with cytogenetic biomarkers. The results of this study does not support the hypothesis of any direct genotoxic effect of ELF-MF, at least at the environmental levels currently found in an occupational settings.