Acute genital ulcers (AGU) have numerous etiologies and are a frequent complaint in the emergency room. Its diagnosis is mostly clinical and initially approached in a syndromic manner. It is based on history, physical examination, and laboratory findings. It is known that genital ulcer can be the first manifestation of Behçet's disease (BD) and its early recognition can prevent clinical complications related to the disease and improve the patient's quality of life. The present article aims to report the case of a patient with an extensive and deep ulcerative lesion of the vulva, who was initially treated with acyclovir due to the suspicion of genital herpes. Subsequently, after the condition worsened and when adequate anamnesis was collected, diagnostic criteria for BD were identified and the correct treatment was started, with therapeutic success. From the above, it is essential that the gynecologist focuses on BD as one of the differential diagnoses for acute genital ulcer.