Foreign body in the urinary bladder is a rare urological presentation and in most cases are due to self-insertion usually for autoerotic stimulation. We presented a case of 16 years old female who presented with history recurrent urinary tract infection for 6 months. After thoroughly work up she was diagnosed to have a pen cap in her urinary bladder. The foreign body in the urinary bladder was detected by abdominal ultrasound, Kidney, Ureter and Bladder (KUB) X-ray did not detect any abnormal radiopaque material in the area of the urinary bladder or upper tract. At cystoscopy, one pen cap was identified and removed successful.