Dysregulation of the cell cycle is known to play an important role in the oncogenic transformation of cells (Johnson et al, 1995) and abnormal expression patterns of cell-cycle-associated cyclin D1 and retinoblastoma protein (Rb) have previously been documented in high-grade VIN lesions (Rolfe et al, 2001; Zamparelli et al, 2001). This evidence concerns the gene RB1 and vulvar intraepithelial neoplasia.