Purpose: Colonic polyposis is less common in children than in adults. The clinical data pertaining to colonic polyposis in children are limited. Children with colonic polyposis have complications associated with numerous polyps, malignant transformation of the polyps, and extraintestinal neoplasms. We studied the clinical spectrum, endoscopic characteristics, and histologic findings of colonic polyposis in Korean children. Methods: We reviewed the clinical data of 37 children with multiple colonic polyps between 1987 and 2009. The mean age at the time of diagnosis of colonic polyposis was 8.0${pm}$3.2 years. Results: Peutz-Jeghers syndrome, juvenile polyposis syndrome, familial adenomatous polyposis (FAP), and lymphoid polyposis was diagnosed in 22, 7, 6, and 2 children, respectively. The most common clinical presentation in children with colonic polyposis was hematochezia. A family history of colonic polyposis was noted in 7 children. The colonoscopic findings of colonic polyposis varied with the size and number of polyps. The majority of polyps were multi-lobulatd and pedunculated in children with Peutz-Jeghers syndrome. The polyps in children with juvenile polyposis syndrome were primarily round and pedunculated. For the children with FAP, the colon was carpeted with small, sessile polyps. There were multiple sessile polyps in the patients with lymphoid polyposis. Surgical polypectomy was performed in 14 children (38%). Intestinal segmental resection was performed in 13 children (35%). Four patients with FAP underwent total colectomy. Four children with Peutz-Jeghers syndrome had extraintestinal neoplasms. No malignant transformation of polyp was identified. Conclusion: Children with colonic polyposis should undergo a careful initial evaluation and require periodic re-evaluation.