Large scale synthesis of oligoribonucleotides has been successfully performed on PEG support by the phosphoramidite approach using t-butyldimethylsilyl to protect the 2’-hydroxyl group of ribonucleoside. By means of this procedure, the dodecamer r(AGUGGUCUUUGU) was synthesized in 98.1% average coupling yield, and 55 mg pure product was obtained from one gram of functionalized PEG. Large scale synthesis of oligoribonucleotides has been successfully performed on PEG support by the phosphoramidite approach using t-butyldimethylsilyl to protect the 2’-hydroxyl group of ribonucleoside. By means of this procedure, the dodecamer r (AGUGGUCUUUGU) was synthesized in 98.1% average coupling yield, and 55 mg pure product was obtained from one gram of functionalized PEG.