We have optimized surface plasmon resonance (SPR) biosensor technology for a rapid, direct, and low-consumption label-free multianalyte screening of synthetic oligonucleotides (ONs) with modified internucleotide linkages potentially applicable in antisense therapy. Monitoring of the ONs hybridization is based on the formation of complex between the natural oligonucleotide probe immobilized on the sensor surface and the ON in solution in contact with the sensor surface. An immobilization chemistry utilizing the streptavidin-biotin interaction was employed to obtain desired ligand density and high hybridization efficiency. It was demonstrated that the sensor is capable of detecting complementary 23-mer ONs in concentrations as low as 0.1 nM with high specificity and reproducibility.