Abstract: Objective To investigate the characteristics, diagnosis and treatment of perineal endometriosis (PEM). Methods Clinical data about 12 patients who were diagnosed with PEM from January 2010 to December 2014 in Chinese PLA General Hospital were retrospectively analyzed.A range of 6–59 months of outpatient follow-up after surgery was conducted for these 12 patients. Results All 12 patients were fertile woman with average age of 31.7 years, and they all had a history of perineotomy or vaginal laceration during vaginal delivery.The main sign or symptoms of PEM were perineal mass or pain corresponding to menstrual cycle.Ultrasound examination was very important in determining the lesions location.All cases had undergone surgical treatment, and 10 (83.3%) of them