A series of 32 human papillomavirus induced lesions derived from epidermis and mucosa was studied for the modulation of filaggrin-profilaggrin (F-PF) expression according to the degree of virus infection as compared to normal skin and mucosa biopsies. This investigation was carried out on frozen sections using indirect immunofluorescence for filaggrin detection and group specific viral antigen and by in situ hybridization with biotinylated probes for viral DNA detection and typing. The 9 cutaneous warts showed an increase of F-PF expression in upper layer cells as compared to normal epidermis, which could be related to the high production of virus (viral antigen and HPV types 1 or 2). The 5 condyloma acuminata displayed also an enhanced expression of these components which was located in several upper layers but virus infection was confirmed in 2 of them with HPV types 6, 11 or 16. The 6 laryngeal papillomas exhibited a granular reactivity pattern for F-PF in suprabasal cell layers with an increase in the upper layers; viral antigen was found in 4 cases and HPV DNA types 6, 11 or 16 were detected in 4 specimens. Conversely among 12 cervical intraepithelial neoplasia, F-PF was expressed only in very superficial layers in few cases, without any correlation with the DNA detection (6, 11 or 16, 18). Taken together these data are suggestive of an intense expression of F-PF in benign lesions which can replicate the virus and a discrete or an absent expression of these components in premalignant or malignant lesions.