The authors present the first case of regression of cystic lesions on brain MRI in a newborn after therapeutic hypothermia in Poland. Multicystic encephalopathy is the most severe form of hypoxic-ischemic encephalopathy and its regression is described very rarely in the literature. Magnetic resonance imaging is an accepted, optimal method of evaluation of the brain and establishing prognosis in children with HIE. After normal pregnancy an emergency cesarean section was performed at 37 weeks gestation due to the markers of intrauterine hypoxia on CTG. The condition of the newborn was serious: 3, 5, 7, 8 points according to Apgar score in 1st, 3nd, 5th and 10th minute of life, respectively. The infant required resuscitation. The cooling procedure lasted 72 hours. The first MRI study was performed at the age of 3 weeks and revealed cavities in the frontal and parietal lobed. The Evans index was 0.33. The second MRI investigation was carried out at the age of 5 weeks. The cavitary appearance did not change, the Evans index decreased to 0.32. The child underwent third MRI at the age of 2 years 4 months. No cystic lesions were found. There were signs of gliosis in their place and focal cortical-subcortical atrophy. The Evans index was 0.28 (within the normal limits). The neuropsychological status of the child at the age of 2.5 years is normal and brain MRI reveals strikingly mild lesions as compared to cavitary injury reported at the age of 3 and 5 weeks. The presented case shows that severe hypoxic-ischemic lesions such as cavities in an infant after cooling procedure do not necessarily mean poor prognosis, as with time even such lesions may regress. Therefore, even after the MRI diagnosis of multicystic encephalopathy the prognosis should be made with care.