Women, who have advanced endometriosis, often have endometriotic ovarian cysts, known as endometriomas. These cysts contain decomposed menstrual blood that looks like melted chocolate…hence the name “chocolate cysts”. These space occupying lesions can cause chronic pelvic pain, pain with intercourse (dyspareunia) and painful menstrual periods, thus compromising quality of life. They can also activate ovarian connective tissue (stroma or theca) resulting in an overproduction of male hormones (especially testosterone). An excess of ovarian testosterone can severely compromise follicle and egg development in the affected ovary. Thus there are two reasons for treating endometriomas. The first is to alleviate symptoms and the second is to optimize egg and embryo quality.Conventional treatment of endometriomas involves surgical drainage of the cyst contents with subsequent removal of the cyst wall (usually by laparoscopy).Unfortunately, with surgery normal ovarian tissue can be  inadvertently removed/damaged along with the cyst wall, thereby decreasing the number of available eggs for harvest. Since many women who have endometriomas also have advanced endometriosis and have had one or more previous surgeries, they often .have significant scarring and adhesions. This can compromise visualization of and access to anatomic structures during conventional laparoscopic surgical correction, increasing the risk of surgical complications. Many patients with recurrent ovarian endometriomas are uncomfortable with the prospect of repeat surgery and its avoidance is often a factor in their decision to proceed with IVF. We recently reported on a new, effective and safe outpatient approach to treating endometriomas in women planning to undergo IVF. We termed the treatment ovarian Sclerotherapy.  The process involves; needle aspiration of the “chocolate colored liquid content of the endometriotic cyst, followed by the injection of 5% tetracycline hydrochloride into the cyst cavity. Such treatment will, more than 75% of the time result in disappearance of the lesion within 6-8 weeks. In some cases the injection of tetracycline into the endometrioma causes a reaction that results in clear or blood stained fluid collecting in the original cyst cavity where the endometrioma had been. Upon re-aspirating the fluid in the seroma, the lesion will usually disappears permanently most times. In a small number of cases, the endometrioma comes back and sclerotherapy must be repeated or surgical removal undertaken. Ovarian sclerotherapy can be performed under local anesthesia or under conscious sedation. It has the advantage of being an ambulatory in-office procedure, low cost, and has a low incidence of significant post-procedural pain or complications and the avoidance of the need for laparoscopy or laparotomy. Sclerotherapy is a safe and effective alternative to surgery for definitive treatment of recurrent ovarian endometriomas in a select group of patients planning to undergo IVF. Since the procedure is associated with a small, but yet realistic possibility of adhesion formation; its use should be confined to cases where IVF is the only treatment available to the patient. Women who intend to try and conceive through fertilization in their fallopian tubes (e.g; following natural conception or intrauterine insemination) are better off undergoing laparotomy or laparoscopy for the treatment of endometriomas.