A total of 121 patients with cervical intraepithelial neoplasia (CIN) in their punch biopsies were treated by LETZ. In all cases, the transformation zone was fully visible and there were no signs of abnormal cylindrical epithelium. The final diagnosis was classified in accordance with the histologic report showing the most severe lesion. The biopsy diagnosis underestimated the final diagnosis in 27 out of the 121 cases. Invasion was present in five out of these 27 cases. The discrepancies between the biopsy diagnosis and the final diagnosis were not related to the number of colposcopically directed biopsies. It is concluded that an important advantage of LETZ, as compared with tissue-destructive techniques, is the detection of previously unrecognized invasive disease.