The present invention is a method of treating or preventing endometriosis by means of administering stem cells to a patient. The stem cells are preferably drawn from umbilical cord tissue and/or umbilical cord blood and are preferably combined with a liquid carrier to form a stem cell solution. In the case of a female patent asymptomatic of endometriosis but at increased risk of developing endometriosis due to at least one endometriosis associated genetic marker being known to exist in the patient, the stem cell solution is preferably injected in the general abdominal/rectal/vaginal area of the patient. In the case of a female patent known to have endometriosis, the stem cell solution may be injected directly into endometrial tissue, and more especially into an endometrial lesion of the patient. The stem cell solution may also be used for treating other disorders such as infertility.
