Eight mesonephric adenocarcinomas of the uterine cervix, four of which had a malignant spindle-cell component, occurred in women aged 34 to 71 (median 43, mean 54.5) years, bringing to 14 the number of cervical mesonephric carcinomas in the literature. The tumors with a malignant spindle-cell component ("malignant mesonephric mixed tumors") are, with one possible exception, the first reported examples at this site. The patients, almost all of whom presented with vaginal bleeding, underwent hysterectomy; five also had a pelvic lymph node dissection. The tumors were all stage IB, although microscopic lymph node metastases were found in two cases. Gross examination revealed an invasive cervical mass in each case. On microscopic examination, seven tumors were adjacent to mesonephric hyperplasia, which in five cases was florid and focally atypical; in the remaining case, occasional non-neoplastic mesonephric tubules were found only within the tumor. The adenocarcinomas typically exhibited a variety of patterns, including a ductal pattern resembling endometrioid adenocarcinoma, a small tubular pattern, a retiform pattern, a solid pattern, and a sex-cord-like pattern. These disparate patterns frequently caused diagnostic difficulty. The spindle-cell component generally resembled endometrial stromal sarcoma or a nonspecific spindle-cell sarcoma; one tumor also contained multiple foci of osteosarcoma and another, a single chondroid focus. Immunohistochemical staining for a variety of antigens failed to reveal a distinctive profile, although all the carcinomas were immunoreactive for vimentin. Follow-up in six cases revealed three patients to be alive without evidence of recurrence at postoperative intervals of 2 to 3 years. Recurrent tumor developed in a fourth patient 1 year after hysterectomy; she was treated with chemotherapy and was alive and free of disease at 2 years. Another patient had intra-abdominal recurrences (including liver metastases) at 9 and 11 years and was alive with tumor at 13 years. Death at 8.5 months in a final patient was probably due to an independent stage IIc ovarian clear-cell carcinoma. These and prior observations in the literature suggest that malignant mesonephric tumors of the cervix may be more indolent than their müllerian counterparts, from which they should be distinguished. Mesonephric carcinomas in this site should also be distinguished from florid mesonephric hyperplasia, with which they are usually associated.