Background: The aim of this study was to investigate the effect of extremelylow frequency magnetic fields (ELFMF) on the uterus and ovary of rats. Material/Methods: Forty-eightfemale Wistar albino rats were divided into two groups, one for 50 and the other for 100 days of exposure.Each group was further divided into two groups, one sham exposed (n=12) and the other the experimentalgroup (n=12). The experimental rats were exposed to 50-Hz 1-mT ELFMF for three hours/day for 50 or 100days. The sham groups of rats were kept under the same circumstances without applying ELFMF. Electronmicroscopic examination was performed to evaluate the ovaries and uterus. Results: Ultrastructural dissolution,decrease in cell organelles, cavities in cells, heterochromative appearance, and typical structural lossof the nucleus were observed in germinal epithelial cells of the rat ovaries in the 50-days ELFMF exposuregroup. Ultrastructural alterations in germinal epithelium and tunica albuginea of ovaries, irregularityin nucleus and nucleolus, increase in lipid vacuoles of cell cytoplasm and reduction in organelles wereobserved in rat ovaries in the 100-days ELFMF exposure group. Similar alterations were observed in uterus.Malondialdehyde concentration (MDA) of the ovaries and uterus increased in rats of the two exposure groups(p

Keywords: Magnetics, Microscopy, Electron, Ovary - ultrastructure, Uterus - ultrastructure