Abstract: A method for the amplification of a template nucleic acid comprises simultaneously carrying out the steps of reacting a nucleic acid primer with said template nucleic acid, normal DNA precursor nucleotides, at least one modified DNA precursor nucleotide and a DNA polymerase so as to obtain an extended nucleic acid primer, said nucleic acid primer remaining bound to said template; cleaving the modified base-containing extended nucleic acid primer so as to generate a free 3′-OH terminus that is extendible by said DNA polymerase; and repeating steps i) and ii) on DNA fragments thereby generated. The modified precursor nucleotide may be a substrate for a DNA glycosylase or recognised by a 3′-endonuclease and determines the cleavage of the DNA and the site of the cleavage accordingly.