Trisomy 1 is a rare chromosomal anomaly and has never been reported in Korea. Clinical features of trisomy 1 include macrocephaly, prominent forehead, flat nasal bridge, low set ears, and micrognathia, all of which result in a very distinguishable facial structure. A child with trisomy 1 also suffers from mental retardation and/or developmental delays. In this case report, the child was diagnosed with de novo trisomy 1 without receiving any treatment until visiting our hospital. The child suffered from foot and ankle deformities, leading her unable to stand independently. Here we report the surgical treatment and rehabilitation treatment that enabled the child to walk independently.