We describe a case of an endocervical heterologous mesodermal adenosarcoma, found in a 43 year old woman. Among mesodermal neoplasms, various histological types are distinguished: the carcinosarcoma, the embryonal rhabdomyosarcoma or botryoid sarcoma, and the adenosarcoma; the last is formed by a benign epithelial component and by a malignant stromal component, that may contain heterologous tissues, such as cartilage, skeletal muscle, etc. Adenosarcoma is a tumor of the uterine corpus and seems to be most common among menopausal women. A primitive adenosarcoma of the uterine cervix is very rare; in fact the overall percentage of the uterine cervical sarcoma is 0.2-0.4%. The patient, age 43 years, with regular menstrual bleeding came to an outpatient clinic referring a post coital metrorrhagia. After a control examination, a polyp from the uterine cervix was removed; the histopathologic diagnosis was: fibroangioadenomatous polyp of the isthmus with cartilaginous metaplastic areas. Two months later, the patient was referred to our clinic and another cervical polyp was removed. The histological diagnosis was adenosarcoma with chondrosarcomatous heterologous mesodermal component. Then the patient was operated and the postoperative histological examination confirmed the preoperative diagnosis. A literature review about the uterine adenosarcoma etiopathogenesis is reported, and a suitable diagnostic iter, is discussed.