Objective To evaluate whether high-fat diet-induced obesity affects ovarian function in rats and tocontribute to an understanding of the mechanisms involved. Methods Female 5-week-old Wistar rats were fed a high-fatdiet (HFD group, n =40) or a normal diet (control group, n = 40). After 2 months of feeding, the estrous cycle and thenumber of cells in each stage of rat follicular development were evaluated. The levels of serum progesterone and estradiol ineach group were also measured. Male and female rats (1 ∶2) were then mated over a period of 1 week. Results HFDinduced obesity and hyperglycemia, without altering levels of serum triglycerides, cholesterol, or C-reactive protein. HFDalso altered ovarian function by prolonging diestrous phases, decreasing serum estradiol concentrations, and increasing thenumber of antral atretic follicles. Moreover, the HFD group developed follicular cysts and became pregnant later thancontrol group rats. Conclusions HFD induces follicular cyst development and disturbs the ovulatory process, leading to delayed pregnancy.