We report a case of Bowen's disease on the sole presenting clinically as an exophytic, blackish-grey, verrucous tumour, and showing human papillomavirus (HPV) type 16 on analysis with polymerase chain reaction. Positive stains for HPV particles by immunohistochemical analysis were limited to several cell nuclei at the upper stratum Malpighii. However, all the tumour cells in the epidermis exhibited strong and diffuse nuclear and cytoplasmic stains for the tumour suppressor protein p16INK4a. We speculate that dysregulation of the retinoblastoma/p16INK4a pathway may be involved in the pathogenesis of the lesion, and p16INK4a overexpression might serve as a useful surrogate marker for identifying Bowen's disease harbouring high-risk types of HPV infection.