Macroscopic visualization of flat vulval warts is usually obtained by application of 3-5% acetic acid for 2-5 min. However, we have recently seen two women with symptoms suggesting the presence of condylomatous vulvitis where the use of 5% acetic acid for 10-15 min. was necessary for aceto-white lesions to develop. In both women, histologic examination indicated the presence of a Human papillomavirus infection. Prolonged application of acetic acid 5% should be considered among women in whom vulval papillomavirus infection is suspected.