Undifferentiated uterine sarcomas (UUS) are rare and aggressive tumor with scarce data on the outcome and best treatment. We aimed to describe the behavior among patients with UUS at our institution.

Thirteen patients with UUS treated in our centre from 1979 to 2010 were analyzed. Statistics: descriptive analysis for frequencies and Kaplan–Meier actuarial method for overall survival (OS).

Patients mean age was 66 years. Three had FIGO 2009 stage IA, five IB, two IIB, and three IVB. Ten patients underwent surgery and eight received postoperative radiotherapy. Three patients received adjuvant chemotherapy. The median follow-up was 16 months (2–276 months). Stage I patients developed two local relapses and three distant metastases (DM). DM was also observed in stage II patients and in 61.5 % of the entire series. Fifty percent of patients receiving radiotherapy remain alive without relapse. The median OS was 16 months, being 17 months for stage I and 9 for the remainder.

Poor outcome of UUS was associated with a high incidence of DM. Stage I had the best outcome. Radiotherapy seems to have benefited patients, with 100 % of local control and 50 % of long-term survivors. The high incidence of metastasis suggests the need for more accurate initial assessment.