The main purpose of this article is to discuss 2'-protection in the context of effective oligoribonucleotide synthesis. Emphasis is placed on the 2'-protecting groups of choice in the synthesis of oligo-and polyribonucleotides, and the requirements that a protective group must satisfy to become the 2'-hydroxyl-protecting group of choice. Finally, the unit discusses the issue of 2'-O-acyl and 2'-O-silyl group migration to the 3'-hydroxy function of ribonucleosides during protection, along with the consequences of the conditions used for their removal on the stability of internucleotide linkages.