P16INK4a has recently been described as a surrogate marker for HR-HPV associated squamous and glandular intraepithelial lesions of the cervix. The immunohistochemical staining pattern of p16INK4a in high grade intraepithelial neoplasia of the cervix (CIN 2 and 3) is diffuse, whereas in CIN 1 different staining patterns (diffuse, sporadic, focal or negative) can be seen. The aim of our study is to find out whether the p16INK4a staining pattern of CIN 1 is able to predict the outcome of the lesion. The retrospective part of the study includes cervical biopsies of 200 patients with CIN 1 and clinical follow-up for at least 5 years. p16INK4a staining and HPV detection by IHC will be correlated to clinical outcome.The prospective part of the study includes 300 patients with CIN 1 and LSIL on cytology. HPV detection by HCII and p16INK4a immunohistochemistry on liquid based cytology samples as well as p16INK4a staining and HPV detection by ISH on colposcopy guided biopsies will be correlated to clinical follow-up and colposcopy findings. Slides are analysed by 2 pathologists without knowledge of clinical data.