The prevalence of human papillomavirus in cervical lesions with koilocytosis and/or CIN I. APMIS 100: 280-286, 1992. Thirthy-one patients with koilocytosis and/or concomitant CIN I were analysed for the presence of HPV types 11, 16 and 18 by in situ hybridization and Southern blot analysis. The prevalence of HPV was 48%) and 55%, respectively, when measured by the two methods and among the HPV positive, HPV 11 and 16 were present in 47% and 60%, respectively, whereas HPV 18 was not found.Clinical epidemiological studies support the hypothesis that precancerous and cancerous lesions of the uterine cervix are related to human papillomavirus (HPV) infection (1,9,16,17, 33, 34). Distinct subtypes of HPV have been demonstrated in 60-100% of precancerous and malignant lesions of the cervix, and an essential event in the malignant transformation may be the integration of the viral genome into the chromosomal DNA (7,24,27, 32). More than 60 HPV types and subtypes have been cloned and characterized (6). At present more than 20 different HPV types have been associated with infections in the genital mucosa. HPV 6 and 11 are most frequently found in genital condylomas and in lower grade cervical intraepithelial neoplasia (CIN I) (reviewed by Bosch & Munoz (1). The HPV types 16, 18, 31, 33, 35, 45, 51, and 52 are most often associated with higher grades of dysplasia (CIN I1 and CIN III/CIS) and invasive carcinoma of the uterine cervix (1). The prevailing types are HPV 16 and 18, which can be demonstrated in 60-100% of specimens with CIN 11, 111 and invasive cancer (1, 32). Typing of HPV in early lesions is believed to be of prognostic value and allows identification of possible risk groups. It is therefore desirable to develop diagnostic methods which are reliable, fast and inexpensive. Genital lesions are detected by clinical examination and by analysis of histological and cytological specimens, but identification of HPV types is only possible by nucleic acid hybridization or polymerase chain reaction (PCR) (14,18, 32).Brigati, D. J., Myerson, D. & Leary, J. J.: Detection of viral genomes in cultured cells and paraffin-embedded tissue sections using biotin-labeled hybridization probes. J. Virol. 126: [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] 1983. Campion, M. J., McCance, D. J., Cuzick, J. & Singer, A.; Progressive potential of mild cervical atypia: prospective cytological, colposcopic, and virological study. Lancet Aug 2: 237-240, 1986. Caussy , D., Marrett, L. D., Worth, A. J., McBride, M. & Rawls, W E.: Human papillomavirus and cervical intraepithelial neoplasia in women who subsequently had invasive cancer. Can. Med. As-Collins, J. E., Jenkins, D. & McCance, D. J.: Detection of human papillomavirus DNA sequences by in situ DNA-DNA hybridization in cervical intraepithelial neoplasia and invasive carcinoma: a retrospective study. J. Clin. Pathol. DeVilliers, E. M.: Heterogeneity of the human 135-151, 1989. SOC.