The overall prevalence of vulval involvement in women with lichen planus is unknown. In a series of 37 women with lichen planus, we found vulval lesions in 19 (51%). Vulval lesions are often chronic and may undergo malignant change. All patients presenting with cutaneous or oral lesions of lichen planus should be questioned about, and examined specifically for, signs of genital involvement. Long-term follow-up of these patients is necessary.