Beginning with a replication of previous experiments (of the Vienna group, S. Ivancsits et al, Int. Arch. Occup. Environ. Health 76 (2003) 431–436), where it was reported that ELF-EMF affected DNA integrity in human cells based on Comet assay, this study set out to clarify the existence and explore the origin and nature of ELF-EMF induced DNA effects. In conclusion, the results confirm that intermittent (but not continuous) exposure of human primary fibroplasts induces an increase of DNA fragmentation in the Comet assay. The conducted experiments further suggest that the effects can be explained by minor disturbances in S-phase processes and occasional triggering of apoptosis rather than by the generation of DNA damage. Due to its depth, the study may constitute an important milestone in low intensity BioEM research.