The MR images obtained of brain during the process of myelination taking place from birth to 2 years of age are analyzed. Basically, the study focuses on the changes in signal intensity experienced by the elements of the brain in the different sequences, consisting in an increase (T1 weighted sequence) or decrease (T2 sequences) in the signal. The chronological evolution of these changes is compared with the classic myelination pattern, described prior to the development of MR, based on necropsies. Also assessed were the progressive changes in the signals of the gray and white matter, reflecting their hydric contents, throughout the period of maturation of the brain structures. It is concluded that MR imaging is presently the diagnostic method of choice in the monitoring of myelination. MR spectroscopy studies offer important perspectives for assessment and follow up of this process from the metabolic point of view.