Objective: Clonality, the property that the cells within a tumor are derived from a single parent cell, is often indicated by uniformity or relative uniformity of genetic aberrations contained within many or all cells of the tumor. The aberrations are assumed to confer or reflect biological distinctions relevant to tumor behavior, and thus to be relevant to tumor initiation and clonal expansion. We investigated the contribution of promoter methylation-mediated epigenetic events in recurrent laryngeal papilloma (RLP) tumorigenesis.