Arsenic compounds have been widely used in pesticides, herbicides and soil disinfectors, thus in some soils, its concentration was very high. Groundwater arsenic concentration was increasing in many parts of the world in last few decades. Arsenic is a highly toxic metal element that annually threatens the health of millions of people in the world. The increase of these pollutants in the environment is considered as a serious threat to human and environmental health. Groundwater arsenic contamination was high in many countries including India. The microbial processes for bioremediation of toxic metals employ living cells, non-living biomass or biosorbents. A wide variety of fungi and bacteria are now under study. Thus the present study is designed to evaluate the cytomodulatory effect of Lactobacillus sporogenes on ovary of arsenic-exposed mice. Sodium arsenate was administered 5 mg/kg b.wt for 4 weeks was followed by the administration of Lactobacillus sporogenes for 8 weeks at 15 million spores/kg body weight. Serum was collected for hormonal study. The ovary was fixed for light microscopic study. Estrogen level was increased 30 folds in the arsenic administered group of mice. Degenerated germinal epithelium and corpus luteum were observed. Degenerated ova and mature Graffian follicle were also observed in the arsenic administered group. Lactobacillus causes marked restoration in estrogen level and ovarian follicles including ova. It is concluded from the entire study that Lactobacillus causes effective restoration in estrogen level. It also maintains Germinal epithelium, follicular stages, corpus luteum and ova in the ovary of mice. This indicates that Lactobacillus maintains normal female fertility in mice.