The third well-documented case of an oesophageal squamous cell papilloma in the literature is studied by light microscopy and using an indirect immunoperoxidase-PAP technique. Human papilloma virus (HPV) antigens were found within the nuclei of the superficial dyskeratotic cells and of koilocytes, both of which are characteristic cells found in HPV lesions elsewhere in the body. The findings are discussed in the light of current concepts of HPV lesions in general. It is suggested that this tumour is potentially malignant and that the possible role of HPV in human oesophageal carcinogenesis deserves further study.