Colposcopic expertise is necessary in cases of cervical intraepithelial neoplasia (CIN) to avoid conservative treatment of microinvasive and invasive lesions. Large loop excision of the transformation zone (LLETZ) enables the pathologist to examine the entire tumor, and especially its margins. We describe this method and its indications, and review the results of our first 100 cases (mean age 28 years, range 19-46). Indications for LLETZ were biopsy findings of CIN III or of a large CIN II, a lesion entering the endocervical canal, and recurrent CIN after CO2-laser treatment. The procedure was performed under local anesthesia in 93 patients; complications were minimal (8 cases of bleeding requiring local tamponade). In 14% marginal involvement was found, but in only 4 was re-treatment necessary during follow-up of 12-33 months. Only 3 developed recurrent CIN, which was again treated by LLETZ. The cure rate of the initial treatment was 97%. This ablative, nondestructive method is easy to perform, requires only local anesthesia, has few, mild complications and gives an accurate histopathological result, including information on margins. The procedure is becoming the method of choice for treating high-grade and recurrent CIN.