Posterior deeply infiltrating endometriosis (PDIE) is an invalidating disorder that may involve the rectosigmoid colon. MRI with gel opacification after rectosigmoid colon cleansing improves visualization of rectosigmoid endometriosis. Nonetheless, the depth of bowel wall infiltration is still difficult to assess. In this regard, the use of high-frequency echoendoscope may be needed. Recognition of rectosigmoid endometriosis is important to establish a correct diagnosis and provide counseling and appropriate therapy.