Background: Insertion of rectal foreign bodies intentionally or unintentionally is not unusual. Case presentation: A 19-years-old unmarried male was admitted to our hospital due to a lump of left lower quadrant of abdomen. He denied sexual assault .The abdomen was soft on physical examination. Abdominal x-ray and CT scan showed a foreign body in lower abdomen and pelvis. The patient was operated and a slice of glass was extracted. Conclusion: In patients with rectal foreign body, the history is not always reliable and sexual assault may deny. The foreign object inserted in the rectum may migrate to peritoneal cavity without peritonitis.