We describe a unique case of a 67-year-old patient with primary uterine rhabdomyosarcoma with a history of breast cancer and gastrointestinal stromal tumor of the stomach. Uterine rhabdomyosarcoma was diagnosed in our patient during adjuvant treatment of breast cancer with anastrozole. To the best of our knowledge, the development of primary uterine rhabdomyosarcoma has never been described in patients treated with anastrozole. Due to the suggested causative role of tamoxifen in the development of uterine sarcomas, it is interesting to analyze whether the new drug, anastrozole, exerts any pathogenic effect on the development of uterine sarocomas.