Very specific properties of nanoparticles such as size, shape and high surface to volume ratio make them appropriate for medicinal and biological applications. These matters are distributed in organs and tissues rapidly after injection and are absorbed by cells highly. This study was carried out to investigate the effect of titanium dioxide nanoparticles on ovarian tissue of female mice. Forty female mice were divided into four groups: control group did not receive anything, placebo group and two experimental groups which received 10 and 100ppm of nanoparticles via gavage. At the end of period ovaries were colored using hematoxylin-eosin method and studied using light microscopy. Obtained data were analyzed using SPSS software. According to results, 10 ppm group was not significantly different from control group but 100ppm group increased graafiam follicle and corpus luteum significantly. Titanium dioxide nanoparticles can enforce ovarian tissue changes and therefore this nanoparticle can affect female reproduction potential dose dependently.