As a result of finding novel ribonucleic acid (RNA)'s and identifying their functions, it is now known that RNAs play a very important role for living organisms. Particularly, the ncRNAs (non-coding RNAs), which cover 62% of the genome, participate in the regulation of important processes such as cellular defense, development, differentiation, DNA replication, transcription and post-transcriptional silencing. Not surprisingly, therefore, their disruption has been linked to diseases such as cancers, neurodegenerative diseases, immunodeficiency, and cardiovascular diseases. ncRNAs have become the targets and tools of novel therapeutic approaches. By the help of identifying all functional ncRNAs that are encoded in the human genome, new therapeutic approaches may be developed and clinical trials using ncRNA-based molecules may be achieved. In this paper, we review the literature regarding the types of ncRNAs, their relation to diseases, and new diagnostic-therapeutic approaches.