Müllerian adenosarcoma is an uncommon biphasic tumor composed of a malignant stromal component admixed with a benign glandular epithelial component. The tumor occurs mainly in the uterine corpus but also as a primary lesion in the uterine cervix, ovary, vagina, fallopian tubes, or even outside the female genital tract. While the tumor may arise from a wide range of anatomic sites, so far only two cases with synchronous occurrence of adenosarcoma have been published. Here the authors present a case of a 64-year-old woman with synchronous Müllerian adenosarcomas in the uterine cervix, bilateral ovaries, left fallopian tube, and endometrium. This case is also the first reported case with synchronous adenosarcomas involving more than two anatomic sites.