Low grade endometrial stromal sarcoma (LGESS) is a rare disease. LGESS usually expresses steroidal receptors and is regarded to be hormone-sensitive. Due to the rarity of the tumor, only few case series have been published so far. Here, we report the case of a 36-year-old woman who underwent an abdominal hysterectomy with bilateral salpingo-oophorectomy and adjuvant radiotherapy for a G1 LGESS in 1991. Twelve years later she presented to us with pelvic and peritoneal masses. The patient was treated with letrozole achieving a partial response which is lasting 39 months. Treatment is ongoing. Aromatase inhibitors represent an interesting treatment option for LGESS.