Nucleopeptide Phac-Ser(p(5')CATCAT)-Gly-Asp-OH, corresponding to the linking site of adenovirus-2 nucleoprotein, has been synthesised by a stepwise solid-phase methodology. After assembly of the peptide on a solid support, the oligonucleotide chain elongation was carried out at the hydroxyl group of the serine residue by the phosphite triester approach using 5'-phosphoramidite derivatives. The target nucleopeptide was then obtained in good yield after removal of the permanent protecting groups under mild basic conditions.