The authors describe a unique case of osteosarcoma associated with atypical mesonephric rests occurring in the right lateral wall of the uterine cervix. The tumor was examined histologically, cytologically, immunohistochemically, and ultrastructurally and was compared with another osteosarcoma that filled an entire uterine cavity. Comparison with other neoplasms of the uterine cervix indicates that the lesion should be classified separately. Previously reported neoplasms associated with mesonephric rests within the cervix are also reviewed.