A 21-year-old woman was admitted to our hospital with a complaint of voiding-difficulty and urinary retention. On examination, the labia was found to be extensively fused with a pinhole opening in the center of adhesion from which urine discharged. The fusion was separated surginally under the diagnosis of labial adhesion. Labial adhesions generally occur in children or post-menopausal women, but are extremely rare in reproductive women. This is the sixth case of labial adhesion in a reproductive woman reported in Japan.