This paper presents the cellular proliferation effects of the exposure to extremely low frequency electromagnetic fields (ELF-EMF) on in-vitro cellular cultures HeLa and CHO. Through the magnetic stimulation system (MSS) the cells were exposed to magnetic fields with sinusoidal waveform at 50 Hz; initially for 40 minutes at intensities of 0.4 mT, 1.4 mT, 2.13 mT, 2.49 mT and 2.53 mT in parallel and perpendicular directions to the culture plates. Subsequently, the repetitive electromagnetic field (rEMF) was applied to 2.49 mT in parallel direction (for 40 minutes every twelve hours during 4 days) with which the highest cellular proliferation rate was obtained at 66.6 %. The results show a greater effect on proliferation in radiated cell lines, particularly in the application of rEMF a greater effect of ELF-EMF was observed in the proliferation rate of HeLa cells than in CHO cells, in contrast to the respective control cells. These results supported by other studies serve as a reference in the search for alternatives for the treatment of cervical cancer and the maintenance and preservation of cell lines.