Uterine smooth muscle tumors of uncertain malignant potential, or STUMP, form a rare group of tumors that fall neither into the benign nor malignant categories. Two cases are reported, describing diagnosis, known prognostic factors, and therapy. In contrast to leiomyomas and leiomyosarcomas, many uncertainties still exist concerning prognosis and postoperative management of STUMP, because of their rarity. Diagnosis is usually not made preoperatively, but by postoperative anatomo-pathological examination. There are histological and immunohistochemical factors that could be associated with a worse prognosis, but scientific evidence is insufficient. Most cases show a low risk of recurrence, although individual risk is unpredictable. Recurrences mostly occur after a long disease-free interval. A conservative approach with strict long term clinical follow-up is therefore indicated. Further research must be conducted to identify surgical procedures that have a higher risk for recurrence. After a laparoscopy, where the specimen was morcellated, the possibility of peritoneal spread and the difficulty in examining section margins, need to be taken into account. Further treatment therefore needs to be individualized.