Most of the available evidence supports the hypothesis that endometriosis compromises fertility. According to ESHRE 2005 guidelines for the diagnosis and treatment of endometriosis, treatment with intrauterine insemination (IUI) improves fertility in minimal-mild endometriosis: IUI with ovarian stimulation is effective but the role of unstimulated IUI is uncertain. Lower pregnancy and implantation rates have been documented in women with severe (stage III or IV) endometriosis when compared to mild (stage I or II) endometriosis. Assisted Reproductive Technology (ART) may bypass some of the mechanisms of endometriosis-associated infertility, but the disease may have an impact on cycle outcome. Oocyte donation appears as an alternative in patients with endometriosis with low response, poor embryo quality, or repeated ART failures. Surgery for endometriomas in women undergoing ART is indicated in symptomatic women; otherwise, it does not add any benefit to cycle outcome. However, careful surgery does not compromise ovarian reserve.