Many aspects of endometriosis continue to make it an enigmatic medical condition nearly a century after its first description as a specific disease. The Endometriosis Fertility Index (EFI) is the first validated scoring system that is predictive of nonassisted reproductive technologies pregnancy following surgical evaluation when the patient has functional gametes and uterus. Pregnancy rates decrease significantly in patients with decreased ovarian reserve, which is especially a problem in older patients and also, as reflected in the EFI, decrease over time if pregnancy does not occur in the first year or two following surgery. Patient management algorithms using this information to assist in deciding when to continue nonassisted reproductive technologies vs. assisted reproductive technologies attempts at conception are presented.