The carbon dioxide laser was used to treat 138 patients with cervical intraepithelial neoplasia between February, 1979, and February, 1981. All patients in this study were assessed in the colposcopy clinic prior to treatment. The diagnosis of cervical intraepithelial neoplasia was based on colposcopic examination, cytologic findings, colposcopically directed biopsy, and endocervical biopsy in all cases. Included in the 138 patients were 26 with grade 1, 82 with grade 2, and 30 with grade 3 cervical intraepithelial neoplasia. The persistence rate of abnormal cytologic findings at 7 months after treatment was 11% for grade 1, 8.5% for grade 2, and 10% for grade 3 cervical intraepithelial neoplasia. No major complications accompany this treatment modality, which was performed in the outpatient clinic without the use of anesthesia or analgesia.