UNLABELLED: What's known on the subject? and What does the study add? The clinical presentation and complications of lichen sclerosus are well known. What is less well known is the true incidence of the condition. The published figures are all based on attendance at general medical clinics or specialist clinics, but it is likely that the true incidence is much higher than this reported incidence as many men will not present to the doctor for treatment. The other uncertainty is the relationship of lichen sclerosus to the subsequent development of cancer of the penis. As pointed out in the paper, it is likely that between 4% and 8% of men with this condition will develop squamous cell cancer of the penis. However, it is unclear if lichen sclerosus itself causes the development of squamous cell cancer or if it is due to coexistent infection with human papillomavirus. This review provides a concise summary of the clinical and pathological features of the disease and describes its current medical and surgical treatment. It brings together a number of papers which have addressed the association of lichen sclerosus with squamous cell carcinoma of the penis and shows that the likely incidence of carcinoma is approximately 4-8% in men with this condition. SUMMARY: Penile lichen sclerosus, also known as balanitis xerotica obliterans, is a chronic inflammatory condition of the penis which can occur at all ages. The inflammation leads to the formation of white plaques most commonly on the foreskin or penis, and can lead to inability to retract the foreskin or blockage to the flow of urine. Cancer may occur rarely. Penile lichen sclerosus is a progressive, sclerosing, inflammatory dermatosis of the glans penis and foreskin which is of uncertain aetiology. Recent studies have shown a link between lichen sclerosus and squamous cell carcinoma of the penis. In this review, we discuss the clinical presentation, pathology and current approach to treatment of this condition.