The term 'brain plasticity' means the brain capacity to diminish the effects of the lesions through structural functional changes. A great part of the pathological processes of the nervous system affecting the corticospinal and the subcorticospinal tracts, the cerebellar, spinal, visual, language and other systems show neuronal plasticity, spontaneously in some cases and after suitable rehabilitation in others. The clinical manifestations of neuronal plasticity are observed especially after prenatal, neonatal or childhood cerebral damage. During the adulthood, the brain has less capacity of neuronal plasticity, although plastic changes may be found at any age. Apart the clinic, the neuronal plasticity can be studied through electrophysiology, MR, positron emission tomography (PET), transcranial magnetic stimulation (TME), and obviously by histology, this latter especially in experimental studies. In pediatric Neurology, the concept of brain plasticity is frequently used to explain the favourable clinic evolution in a lot of cases with severe brain injury.