Freezing of gait (FOG), which is the most common symptoms in Parkinson's disease, is a unique gait disorder that patients are unable to initiate or continue locomotion. However, the pathophysiology of FOG has been poorly understood. We report two cases, one case is a 26-year old man and the second case is a 65-year old man, who showed FOG following hypoxic brain injuries caused by sudden cardiac arrest and hypovolemic shock, respectively. Brain F-18 FDG-PET images demonstrated the diffuse cortical hypometabolism in case 1 patient, and the decreased metabolism of the subcortical structures in case 2 patient. Two patients showed the typical features of FOG (turning, destination, and tight quarter hesitations combined with kinesia paradoxa) and the abnormal patterns of temporospatial data in kinematic gait analysis. We present two cases of FOG following hypoxic brain injury with reviewing of some literatures.