The object of this study was to determine the efficacy and safety of brain hypothermia therapy (BHT) for neonates with severe birth asphyxia in our neonatal intensive care unit (NICU). We retrospectively reviewed medical records to analyze the prognosis and the factors affecting the prognosis of 21 patients who underwent BHT at the NICU between 2001 and 2007. The prognosis of those 21 patients at the time of discharge from the NICU was as follows: good-11 patients (52.4%); disability-5 patients (23.8%); and death-5 patients (23.8%). The ten poor prognosis patients (disability: 5, death: 5) had a shorter gestational period, a lower Apgar score, and a significantly higher blood lactate level in comparison with good-prognosis newborns. In particular, a gestational period of less than 34 weeks (3 patients) and a blood lactate level of at least 200 mg/dl (6 out of 7 patients) are considered to be factors for a poor prognosis. In addition, intraventricular hemorrhage was recorded in 7 patients of the 10 poor-prognosis patients and 4 of those patients developed acute renal failure during BHT. Consequently, these disorders are considered to worsen the prognosis. This study supports the efficacy and safety of BHT for neonates with severe birth asphyxia. On the other hand, BHT for the above mentioned types of high-risk patients still requires further consideration for the adoption and methods of BHT.