BACKGROUND Incidence of ovulatory disorders is common in obese animal models. The mechanism behind this effect is not clear. We hypothesized that high fat (HF) diet induces alterations in neuroendocrine mechanisms resulting in anovulation in diet-induced obese (DIO) animals. METHODS Adult female DIO and diet-resistant (DR) rats were fed either chow or HF diet (45% calories from fat) for 6 weeks. Oestrous cyclicity and body weight were monitored regularly. At the end of treatment, rats were implanted with a jugular catheter to monitor luteinising hormone (LH) levels on the day of prooestrous. Rats were sacrificed on the following prooestrous, their brains and ovaries were collected. Plasma from trunk blood was analyzed for oestradiol and leptin concentrations. Ovaries were fixed and sectioned for histological analysis. Brains were removed, frozen and sectioned and norepinephrine (NE) concentrations in discrete hypothalamic areas were measured using HPLC-EC. RESULTS HF diet affected oestrous cyclicity in both DIO and DR rats with the effect being more pronounced in DIO animals. HF diet increased leptin levels in both DIO and DR rats. Oestradiol levels were low in the DIO-HF group. NE levels in the hypothalamus were unaffected by HF diet or genotype. A normal LH surge was observed in DR-Chow rats and LH levels were low in the rest of the groups. CONCLUSION DIO rats have an inherently reduced reproductive capacity and exposure to a HF diet decreases it further. A reduction in oestradiol and LH surge levels could contribute to this effect, however the underlying mechanisms need to be studied further.