A wavelength interrogation-based surface plasmon resonance (SPR) biosensor has been investigated for a detection of avian influenza DNA (AI-DNA). The hybridization reaction between AI-DNA and the immobilized oligonucleotide probe on a gold surface was monitored. The results showed that SPR biosensor can provide a linear detection suitable for quantification of AI-DNA hybridization as well as a large dynamic range. The experimental results were consistent well with numerical calculations using rigorous-coupled-wave analysis (RCWA). This study demonstrates the potential of using wavelength-scanning type SPR biosensor in a simple and real-time detection of AI virus.