In this study, we evaluated the cumulative effects of arsenic (III) oxide on the number of mouse offspring over three consecutive generations and monitored changes in levels of the reproductive hormones, oestradiol and progesterone in female mice during the dioestrus phase of the cycle. The control group received water from the mains. In two experimental groups, mice were given drinking water containing dissolved arsenic (III) oxide at concentrations of 10.6 mg L-1 and 106 mg L-1, respectively. These concentrations represent the values converted from a human model to an animal model (mice) thus correspond to the arsenic content of the groundwater in the southern part of the Pannonian Basin, in the province of Vojvodina, in the Banat region, in particular in the town of Zrenjanin. The average number of newborn mice in both experimental groups decreased for three consecutive generations. The total arsenic content of day-old mice did not show significant differences between the experimental groups. Arsenic (III) oxide affected the reproductive hormone levels of female mice at both concentrations.