IntroductionEndometriosis was first described by Rokitansky in 1860. It refers to the appearance of endometrial tissue outside the uterine cavity. The incidence rate of endometriosis in women of childbearing age is about 10%–12%; in 5%–12% of cases, it may involve the intestines[1]. Colorectal endometriosis may lead to myriad symptoms, such as alteration in bowel habits (constipation/diarrhea), abdominal pain, dyspareunia (difficulty in sexual intercourse), and infertility [2], which have a significant impact on the quality of life of the patient. Due to the lack of specificity in clinical manifestations and related examinations (including endoscopy), the diagnosis of colorectal endometriosis poses a significant challenge to physicians [3]. This case was detected during colonoscopy examination. Previous reports have only rarely described the manifestations of this disease under colonoscopy. Here we report a case of colorectal endometriosis and review the relevant literature. By reviewing this case, we hope to increase awareness about the endoscopic manifestations of the lesion, which may improve chances of early diagnosis.