To obtain the product of a nucleic acid amplification reaction by bringing an ampli fied product into contact with an oligonucleotide capable of hybridizing to a stretch of nucleotides of the amplified product, the stretch being situated between the hybridization sites of a pair of primers and subsequently subjecting the hybridization complex to a degradative treatment to prevent the contamination of the amplification reactions.

This process for making the product of a nucleic acid amplification reaction, which amplification reaction employs one of more primer pairs, incapable of being a target for further amplification comprises bringing an amplified product into contact with an oligonucleotide capable of hybridizing to a stretch of nucleotides of the amplified product, the stretch being situated between the hybridization sites of a pair of primers, under conditions which allow the formation of a hybridization complex between the oligonucleotide and the amplified product to occur, the oligonucleotide being modified in such a way that it protects the portion of the hybridization complex where the stretch is located from degradation, and subsequently subjecting the hybridization complex to a degradative treatment under circumstances such that at least the part of the hybridization complex capable of hybridizing to the primers is degraded. Thereby, the contamination of the nucleic acid amplification reaction is eliminated to obtain the objective nucleic acid amplification reaction product.