microRNAs are short, non-coding RNAs, that exert a posttranscriptional control on protein synthesis by mRNA interference. They are involved in normal and pathological embryologic development, as well as in adult life pathology, from myocardial infarction to cancer. There are several brain-specific species of microRNA, showing time-dependent pattern of expression, selectivity for neuronal population, significant roles in correct cellular differentiation and system development. The growing interest in microRNAs extended also in the area of neurodegeneration, some of brain-restricted microRNAs being reported to associate with disorders such as Alzheimer's disease, Parkinson's disease or Huntington's disease. The microRNAs research in the last 3 years offered a considerable amount of information that needs to be integrated in the vast machinery of cellular biology.