OBJECTIVE: Large loop excision of transformation zone(LLETZ) is gaining popularity as an alternative to other ablative or cone methods for the treatment of cervical intraepithelial neoplasia(CIN). The optimal management of CIN after LLETZ, however, remains controversial and the reliable predictors of residual disease after LLETZ have not been consistently identified. This study was performed to identify factors to predict residual disease after LLETZ. METHODS: From August 1993 to July 1995, 133 patients who received subsequent hysterectomy after LLETZ in Department of Obstetrics and Gynecology at Seoul National University Hospital were retrospectively reviewed. Residual disease was defined as positive findings of CIN or further advanced findings in hysterectomy specimen. The age of patients, the severity of disease and the status of resection margin(RM) were analyzed for predictive values of residual disease. The Chi-square test, Fisher's exact test and Student t-test were used for statistical analysis. RESULTS: The residual disease after hysterectomy was negative in 85.7%(114/133) and positive in 14.3%(19/133). Among 19 cases with positive residual disease, 3 cases were revealed to be microinvasive cervical cancer. The mean age of patients with no residual disease was 42.5 years(range; 27-71) and that of patients with residual disease was 49.1 years(range; 33-72). Nine out of 94 cases(9.6%) with negative RM and 10 out of 39 cases(25.6%) with positive RM in LLETZ had residual disease. Two out of 14 cases(14.3%) with CIN II and 17 out of 119 cases(14.3%) with CIN III in LLETZ had residual disease. The success of LLETZ which means no residual disease was influenced by the age of patients(p=0.005) and the status of resection margin of LLETZ(p=0.032). CONCLUSION: The negative resection margin in LLETZ does not always guarantee that there is no residual disease. Close preoperative workup and more aggressive treatment plan(wide conization or hysterectomy) should be considered in patients who has higher possibility of positive residual disease such as old age and positive resection margin in LLETZ.