Ninety-two patients with early invasive carcinoma of the cervix (5 mm or less) treated between July 1977 and June 1990 are reviewed. Eighty patients had squamous cell carcinomas and 12 had adenocarcinomas. The diagnosis was established by conization in 77 of 92 (83.6%) patients. Thirty-six patients (39%) had a depth of stromal invasion of 1 mm or less, 32 patients (35%) between 1 and 3 mm, and 24 patients (26%) between 3 and 5 mm. Forty-four patients were treated with radical hysterectomy and bilateral pelvic lymphadenectomy (RHND). None of these patients had positive lymph nodes. Thirty-three patients were treated with conservative hysterectomy (CH), 4 with modified radical hysterectomy, and 2 with trachelectomy. Six patients received radiotherapy. Three patients were treated by conization only. Two patients developed in situ carcinoma (CIS) of the vagina 12 months after CH for lesions on conization that invaded less than 1 mm. In both cases the cone margins were positive, and in one a microscopic focus of CIS of the cervix was present at the resection margin of the hysterectomy specimen. A third patient developed an invasive lesion of the vagina 25 months after CH for a lesion that invaded 2.5 mm in a cone whose margins were not specified, but the hysterectomy margins were clear. All 3 patients were successfully retreated. The remaining patients are free of disease for a median follow-up of 51 months. The results of the study indicate that CH is adequate therapy for patients in whom the diagnosis of early invasive cervical cancer is established by conization with free margins and the depth of invasion is 3 mm or less. Although only 1 of 24 patients with invasion > 3 mm but < or = 5 mm had a CH, pathologic findings in 18 patients who had RHND suggest that CH would have been sufficient for these since there were no instances of spread to nodes or parametrium.