Infertility is more common in overweight and obese women, with reproductive impairments occurring at many levels of the hypothalamic-ovarian-uterine axis. These impairments lead primarily to longer times to conception and decreased pregnancy rates and have resulted in increasing numbers of overweight and obese women seeking assisted reproduction technologies, such as in vitro fertilization or IVF. Even after undertaking IVF procedures obese women have decreased pregnancy rates compared to moderate weight women, suggesting there may be intrinsic differences in the oocytes of these patients. Definitive data is lacking however, and thus the effect of obesity on oocyte quality remains one of the biggest controversies in reproductive medicine. This review summarizes the studies to date which have yielded information about the effects of obesity on human oocyte quality and pre-implantation embryo development. In addition recent results from our laboratory which clearly demonstrate that diet-induced obesity in mice impairs oocyte developmental competence are discussed.