The Authors studied 54 cervical biopsies using in situ hybridization (ISH) to identify HPV related lesions. 26 biopsies lacked clear cut koilocytotic atypia on histological examination and 28 had a diagnosis of grades 1 and 2 intraepithelial neoplasia. Histological diagnosis of HPV-related dysplasia were studied using ISH with biotinylated probes (Phatogene DNA probe assay Enzo Diagnostics). Probes included HPV types 6/11, 16/18 and 31/35/51. HPV DNA were detected in 18 of 28 (64.3%) cervical biopsies with diagnosis of grade 1 and grade 2 cervical intraepithelial neoplasia with koilocytotic atypia. None of the 26 cervical biopsies equivocal for koilocytotic atypia had detectable HPV DNA with ISH. These results suggest that ISH can be used for the quality control in the histological diagnosis of koilocytotic atypia.