Six cases of endometriosis of the uterine cervix characterized by the exclusive or almost exclusive presence of endometriotic stroma are reported. These cases of "stromal endometriosis" were encountered in women 29 to 64 (mean, 43) years of age. Three of them presented with abnormal bleeding, one presented with weight loss and abdominal swelling due to an ovarian clear cell adenocarcinoma, and two were asymptomatic. None of the patients had a history of pelvic endometriosis. In three cases, red lesions of the ectocervical mucosa were recognized on pelvic examination. Histological examination of the lesions showed well circumscribed foci within the superficial stroma of the cervix that were composed of an admixture of closely packed cells resembling endometrial stromal cells, small blood vessels, and extravasated erythrocytes. Endometrial-type glands were absent in the initial sections in all of the cases, but rare glands were found in deeper sections in one case. Apart from the absence or paucity of endometrial glands, the clinical and pathological features of the lesions were similar to those of previously described cases of superficial endometriosis of the cervix. Because of the pure or almost pure stromal composition of the lesion, however, it can be confused histologically with benign and malignant neoplasms, particularly low-grade endometrial stromal sarcoma and Kaposi's sarcoma.