The purpose of this study was to investigate whether Epstein-Barr virus (EBV) is associated with acetowhite lesions of the portio cervix, demonstrating koilocytosis and/or cervical intraepithelial neoplasia (CIN) I-III. The study group comprised 37 women admitted to the Department of Gynaecology and Obstetrics, Sahlgrenska University Hospital, Göteborg because of pathological colposcopy or cytology of the portio cervix. Colposcopically, all exhibited acetowhite lesions of the portio cervix. Cells were sampled with a cytobrush for examination for EBV and human papillomavirus (HPV) DNA by polymerase chain reaction (PCR) and a biopsy was taken for histopathology. Biopsies from 5 patients positive for EBV by PCR in cervical cell samples were examined by an in situ hybridization technique for EBER (Epstein-Barr virus encoded RNA), RNAs expressed in latent EBV infection. The control group consisted of women attending the Department of Dermato-Venereology at the same hospital for STD check-up. These had a normal cytology and no signs of acetowhiteness of the portio cervix. In the study group, EBV DNA was found in 30% and HPV DNA in 51%. In the control group 57% exhibited EBV DNA and 23% HPV DNA. EBV was not found to be a predictive factor in the development of koilocytosis and/or CIN I-III. HPV was a predictive factor in acetowhite, koilocytotic lesions. No expression of EBER was found in the 5 biopsies examined by in situ hybridization.