Objective: Evaluation of regression and progression of histologically confirmed low grade squamous intraepithelial lesions (LG SIL) in women under the age of 35 in context of positivity of high risk human papillomavirus (HPV HR). Evaluation of sensitivity of PAP smear and HPV HR test in women with LG SIL. Design: Prospective study. Setting: Department of Obstetrics and Gynecology, Charles University Prague, 2nd Medical Faculty, University Hospital Motol. Patients and methods: 166 women with SIL low or repeated ASC-US PAP smear were included to the study. 1 to 3 punch biopsy under the expert colposcopy and HPV HR test were performed in all women. Follow up were done every 6 month in all women with histologically confirmed LG SIL. Results: LG SIL was detected in 120 women. Sensitivity of PAP smear was 72.3 % and sensitivity of HPV HR test 60.2 % in women with LG SIL. 84 women (70 %) were HPV HR positive. Regression of LG SIL was detected in 20 (23 %) HPV HR positive women and in 18 (50 %) HPV HR negative women. This difference is statistically significant (p = 0,0094). Progression of LG SIL was detected in 24 (29 %) HPV HR positive women and in 4 (11 %) women HPV HR negative women. This difference is borderline statistically significant (p = 0.058). Progression of LG SIL to the carcinoma in situ or invasive cancer had not been detected during follow up period. Conclusion: PAP smear is a standard for LG SIL detection in women under the age of 35 and HPV HR test is not so important for LG SIL detection in this group of women. HPV HR test could be useful for prediction of the risk of progression, but positivity of HPV HR in LG SIL cannot indicate surgical treatment (conisation) in this cohort of women under the age of 35.

        Key words: LG SIL, HPV HR test, follow up, progresion, regresion