Endometriosis is often seen in gynecology practice and is treated medically. However, intestinal involvement of endometriosis causing obstruction is relatively uncommon and is hard to differentiate from malignancy before surgery. Herein, we present a case of acute colonic obstruction caused by rectal endometriosis. Repeat colonoscopic biopsy and imaging studies could not differentiate the lesion from malignancy. Segmental resection with anastomosis was performed to relieve the symptom and confirm the diagnosis. We present this unusual disease in general surgical practice and also review the literature. The incidence, symptoms, diagnosis, treatment, and risk of malignancy of intestinal endometriosis are discussed.