The clinical and pathologic features of 51 cases of microinvasive carcinoma of the cervix treated by radical hysterectomy and pelvic lymphadenectomy are presented. Microinvasion was defined as stromal penetration by carcinoma not exceeding a depth of 5 mm from the surface at the point of origin. Patients with confluent patterns and lymphatic invasion were not excluded. Lymphatic invasion was demonstrated in 24% of the patients, but none of the resected lymph nodes from the entire series contained metastatic tumor. Residual invasive disease was present in 9 of 47 patients who underwent conization including 1 in which the residual tumor invaded to 8 mm, although the depth of invasion in the cone biopsy was only 2.5 mm. Factors related to the presence of residual invasive disease included the pattern and extent of invasion and involvement of the cone margin. There were no surgery-related deaths or fistulae in this series; the actuarial survival rate at 5 years was 100%. Simple hysterectomy seems justified if the cone margin is free of tumor since none of these patients has residual disease. In contrast, radical hysterectomy may be indicated if the cone margins are involved in view of high frequency of residual tumor (39%) and the possibility of invasion in the cervix exceeding 5 mm.