The classical concept of endometriosis as a cause of infertility is challenged. Traditionally, both surgical and medical therapy of endometriosis-associated infertility has focused on eliminating or reducing the visible implants. The classic 6-month medical approach has been a failure, and surgery may moderately enhance fertility, but its benefit in the absence of adhesions is still doubtful. Recent studies have shown that endometriosis is characterized by an aberrant response to sex steroid hormones, resulting in pleiotropic dysfunctions of the reproductive system involving the uterine, peritoneal and ovarian micro-environment. Studies on endometriosis and IVF have been highly relevant in revealing the pleiotropic dysfunctions in patients with endometriosis, although the results should be interpreted with caution. The conclusion seems to support the view that infertility in patients with endometriosis is primarily dysfunctional, rather than lesional, in origin. It is concluded that the place of medical therapy in endometriosis should be reviewed and that the surgical approach needs to be complemented by appropriate medical therapy to restore fertility.