Intestinal duplications are rare congenital anomaly found in pediatric age group. Although, ileum is the most common site, there are cases of colonic duplications even in the adult. We report a case of 43 years woman presented with chronic constipation, intermittent colicky abdomen pain and a cystic lump in left abdomen diagnosed as tubular duplication cyst of descending colon. Colonoscopy is a good investigation tool for diagnosis of colonic duplications; however, it may not be true in all cases. She was managed with left hemicolectomy and excision of cyst with uneventful post-operative days. This case has been reported as it is a rare condition.