Large-scale synthesis of oligoribonucleotides has been performed successfully on a solid support by the phosphoramidite approach using levulinyl and tetrahydrofuranyl protection for the 5'- and 2'-hydroxyl groups respectively. A hexamer containing inosine and four fragments of a hammerhead-type ribozyme have been synthesized on a 10 mumol scale for structural studies by NMR spectroscopy and X-ray crystallography.