Endometriosis is the presence of endometrial tissue in abnormal locations outside the uterine cavity. These locations are usually the ovaries, the peritoneum, and the uterine ligaments. Less frequently, the endometrial tissue can affect the perineum especially after surgical procedures or obstetric lesions. In this case report, we describe the case of a patient suffering from pain and swelling, with a sizeable nodule in an old episiotomy scar. Clinical examination, ultrasonography (USG) and magnetic resonance imaging (MRI) helped evoke the diagnosis of perineal endometriosis, and there were no signs of other endometriosis locations. Hormonal treatment was provided at first, but there was no clinical improvement after three months, so the treatment had to be surgical. Histopathological examination of the endometriotic mass confirmed the diagnosis. There were no immediate postoperative complications, and no clinical symptoms or recurrence signs six months and one year after.