Many methods for analysis of SNP based on using the allele-specific amplification technique were reported. In these methods, we must use the highly allele-specific primers. However, the specificity of primer depends on the type of SNP and the nucleotide sequence. In this study, we examined the relation between the specificity of primer and the oligonucleotide sequence for typing of NY95. The NY95 typing is based on a A-T transversion mutation. Results showed that the allele-specific primers which have the 3′-terminal nucleotide substitution and the miss-matched nucleotide at 3-5th position from 3′-terminal were highly specific. Furthermore, when the method in which the opposed allele-specific primers were used in one tube, non-specific amplification were not observed.   Consequently, it seems that the opposed allele-specific primers and the non-specific amplification inhibit each other.