CHS is a rare hereditary fatal disease, if not treated. APs occur in 85% of patients and are usually the main cause of mortality, and HSCT from HLA-matched related and unrelated donors is the only effective treatment for CHS and prevents recurrences of APs. We reviewed the records of three patients with CHS who underwent UCBT at KHCC. Records were examined for clinical features at the time of UCBT, conditioning regimens, morbidities, and outcomes. Conditioning comprised BU, cyclophosphamide, horse ATG, and etoposide. All patients tolerated the conditioning well. Two patients are alive, one with mixed and the other with full donor chimerism; hematologic and immunologic defects of CHS have been corrected in both patients. They show no evidence of recurrences of APs and have normal growth and development. In patients with CHS who lack HLA-matched related and unrelated donors, UCBT is a suitable alternative source of stem cells to restore immunologic and hematologic functions and prevent AP relapses, even in mixed chimeric states. Long follow-up and close monitoring are essential to evaluate the long-term benefits of using UCBT in patients with CHS.