Mullerian adenosarcoma of the uterine cervix generally displays cervical polyps and can be often misdiagnosed as benign endocervical polyps both clinically and pathologically. A 52-year-old woman presented with a two-month history of postmenopausal bleeding. Pelvic examination revealed a large polyp-like mass protruding from the cervical ostium. Two preoperative consecutive biopsies showed a histologic diagnosis consistent with an endocervical polyp. Pelvic magnetic resonance imaging (MRI) depicted a lobulated well- enhancing endocervical mass, suggestive of an endocervical polyp based on the apparent diffusion coefficient (ADC) value. The patient was subjected to total hysterectomy with bilateral salpingectomy. Microscopically, the tumor was composed of epithelial and stromal components. The final pathologic diagnosis was Mullerian adenosarcoma of the cervix. The authors presented an unusual case that demonstrated an endocervical polyp on magnetic resonance imaging and two consecutive biopsies preoperatively.