We are concerned that the use of ablative therapy in the treatment of cervical intraepithelial neoplasia may lead to a failure to diagnose early invasive carcinoma. In view of this, since June 1986, 196 patients considered suitable for laser vaporization were treated by a shallow laser excision cone biopsy instead. The mean age of the women treated was 31 years, and the mean length of the excised specimen, measured after fixation, was 14 mm. All procedures were completed in the colposcopy clinic and took no longer to perform than vaporization. The complication rate was low, and an excellent specimen was available for pathologic examination. In this series, histology on the excised cone revealed that two patients had microinvasive carcinoma and one had adenocarcinoma in situ. In addition, 16 patients had a lesion two or three grades worse on the laser excision biopsy than was predicted by the colposcopically directed biopsy. Because of the inaccuracy of colposcopic biopsy, we now recommend a small laser excision cone biopsy as the treatment of choice for all patients with cervical intraepithelial neoplasia.