This study identifies borderline microinvasive carcinoma of the cervix as a subgroup of microinvasive carcinoma. We define borderline microinvasive carcinoma of the cervix as the infiltration of neoplastic squamous epithelial cells into the stroma where the depth of infiltration is 1 mm or less from the basement membrane of the epithelial surface immediately adjacent to the site of infiltration without capillary-like or lymphatic-like space involvement. In a 20-year review of cervical neoplasia in our institution, 29 cases of borderline microinvasion were identified. None of these 29 patients had recurrent carcinoma. Of our in situ carcinomas, 4.8% were found to be borderline lesions on review. Of our cases initially interpreted as microinvasion, 27.1% were, in fact, borderline lesions. There are better data to establish the criteria for borderline microinvasive carcinoma than there are to establish the absolute depths of invasion that would be unequivocally acceptable as “microinvasion.” Borderline microinvasive carcinoma of the cervix is a lesion which is not metastatic and can be treated by nonradical methods.