Acute genital ulcers are painful and distressing to women and perplexing to the providers who care for them. The differential diagnosis includes sexually and nonsexually transmitted infections, autoimmune conditions, drug reactions, and local manifestations of systemic illness. However, in many cases, no causative agent is identified, and lesions are classified as idiopathic aphthosis. In the setting of fever and acute onset of genital ulcers in girls and women, the term Lipschutz ulcers has been used to describe ulcers associated with an immunologic reaction to a distant source of infection or inflammation. The aims of this article are to review the differential diagnosis and pathogenesis of acute genital ulcers, to offer an evaluation and classification scheme, and to discuss treatment options for the dermatologist who cares for women and girls with vulvar ulcers.