In our hospital, one case of colon duplication was found, and was confirmed by radiological examination,surgery and pathology. This twenty-one year old female has been suffered from intermittent colicky lower abdominalpain and palpable abdominal mass. During the colon examination, the normal colon filled in retrograde manner, andthe single terminal ileum was seen. The anomalous colon filled from the mid portion of the descending colon, endedblindly. An intravenous pyelogram and a small bowel series revealed normal kidney, ureter, bladder and small bowelexcept malrotation of the both kidneys and contrast filled blind end of the duplicated colon located near thepelvic area of the right kidney. The patient was in excellent physical condition, and after admission to thhospital, a operation was performed. The findings were exactly as previously discribed.