Objective. The clinical efficacy of conservative treatment using Nd- YAG laser technique for cervical intraepithelial neoplasia (CIN) was evaluated in a large series of CIN patients based on the long- term follow- up results. Methods. We have treated 2107 women preoperatively diagnosed as having CIN by Nd- YAG contact laser conization with vaporization of the base. Their postoperative histologic findings and clinical outcomes were evaluated. Results. The cone specimen was reported as showing that 1956 (92.8% ) of 2107 cases had no CIN or CIN 1- 3 and 151 (7.2% ) cases had invasive diseases. 1956 cases without invasive diseases were followed up for 16 to 252 months. Incomplete excision occurred in 230 (12.3% ) of 1874 patients with CIN lesion in the cone specimen, but failure rate (persistence or recurrence) was only 1.2% . 192 (83.5% ) of 230 postoperative CIN patients with positive surgical margins showed no abnormal cytology or colposcopy during follow- up period. Preoperative underdiagnosis of biopsy results compared with cytologic or colposcopic findings elevated the risk for incomplete excision and failure rate. Conclusion. The combination of laser excision and vaporization of the base was useful to detect unexpected invasive disease and revealed excellent therapeutic effects for CIN. Preoperative cytologic or colposcopic findings should be taken into account for the conservative treatment of CIN. Objectives. The clinical efficacy of conservative treatment using Nd- YAG laser technique for cervical intraepithelial neoplasia (CIN) was evaluated in a large series of CIN patients based on the long-term follow-up results. Methods. We have treated 2107 women preoperatively diagnosed Their having a CIN by Nd- YAG contact laser conization with vaporization of the base. Their postoperative histologic findings and clinical outcomes were not evaluated. Results. The cone specimen was reported as showing that 1956 (92.8%) of 2107 cases had no CIN or CIN 1 1956 cases without invasive diseases were followed up for 16 to 252 months. Incomplete excision occurred in 230 (12.3%) of 1874 patients with CIN lesion in the cone specimen, but failure rate (persistence or recurrence) was only 1.2%. 192 (83.5%) of 230 postoperative CIN patients with positive surgical margins showed no abnormal cytology or colposcopy during follow-up period. Preoperative underd i. combination of laser excision and vaporization of the base was useful to detect unexpected invasive disease and revealed excellent therapeutic effects for CIN. Preoperative cytologic or colposcopic findings should be taken into account for the conservative treatment of CIN.