Objective: The aim of the study was to evaluate the clinical value of the video colposcopy in screening cervica intraepithelial neoplasia(CIN) in cytological negative and smooth cervices by optically gynecological examination. Methods:The 1050 women, whose cervices had been shown smooth and cytological negative by optical examine, were examined with electronic colposcopy in gynecological clinic, and biopsy was taken when the double abnormality of aceto-white epithelium and iodine negative, and other abnormal images were shown. A retrospective analysis of these cases was performed. Results:(1) The 514 samples from 458 cases, including 458 samples of abnormal tissues under colposcopy and 56 samples of polyp or polypoid tumors by optically, were examined by biopsy. Among them, 68 samples were found to be CIN, including11 cases of CINII/CINIII;(2) The 72 of 1050 cases showed the double-abnormality of aceto-white epithelium and iodine negative. Among them, 64 cases were CIN determined by biopsy. And the positive predictive value of the double-abnormality o aceto-white epithelium and iodine negative under colposcopy was 88.9%, with a false negative rate of 3.3%;(3) Among 458women examined by biopsy, only one of 350 samples from cervical polyp tissue was CIN(0.3%), while 67 of 164 samples from the tissues with abnormal colposcopic images were found to be CIN(40.9%), indicating the close relation between abnorma colposcopic findings and CIN;(4) The results of age-distribution analysis showed that, in the 164 cases with abnormal features under colposcopy, the incidence of double abnormality of aceto-white epithelium and iodine negative was higher in the age o sexual activity, just the same as the age distribution feature of CIN; while single abnormality of iodine negative appeared more in the age of over 50 years. Conclusion: Abnormal features displayed by colposcopy, especially the double abnormality o aceto-white epithelium and iodine negative, has an important significance for the screening of cervical precancerous lesions such as CIN. For this purpose, colposcopy examination is necessary even for the cases of cytological negative and smooth cervices. Objective: The aim of the study was to evaluate the clinical value of the video colposcopy in screening cervica intraepithelial neoplasia (CIN) in cytological negative and smooth cervices by optically gynecological examination. Methods: The 1050 women, whose cervices had been shown smooth and cytological negative by optical examine, were examined with electronic colposcopy in gynecological clinic, and biopsy was taken when the double abnormality of aceto-white epithelium and iodine negative, and other abnormal images were shown. A retrospective analysis of these cases was performed. Results :( 1) The 514 samples from 458 cases, including 458 samples of abnormal tissues under colposcopy and 56 samples of polyp or polypoid tumors by optically, were examined by biopsy. Among them, 68 samples were found to be CIN, including 11 cases of CINII / CINIII ; (2) The 72 of 1050 cases showed the double-abnormality of aceto-white epithelium and iodine negative. Among them, 64 cases were CIN determined by bi opsy. And the positive predictive value of the double-abnormality o aceto-white epithelium and iodine negative under colposcopy was 88.9% with a false negative rate of 3.3%; (3) Among 458 women examined by biopsy, only one of 350 samples from The polyp tissue was found to be CIN (40.9%), while the 67 of 164 samples from the tissues with abnormal colposcopic findings were be CIN (40.9%), indicating the close relation between abnorma colposcopic findings and CIN; (4) The results of age -distribution analysis showed that, in the 164 cases with abnormal features under colposcopy, the incidence of double abnormality of aceto-white epithelium and iodine negative was higher in the age o sexual activity, just the same as the age distribution feature of CIN; while single abnormality of iodine negative appeared more than the age of over 50 years. Conclusion: Abnormal features displayed by colposcopy, especially the double abnormality o aceto-white epithelium and iodine negative, has an important significance for the screening of cervical precancerous lesions such CIN. For this purpose, colposcopy examination is necessary even for the cases of cytological negative and smooth cervices.