A method for nucleotide sequence amplification, which comprises: combining a target nucleic acid having a target nucleotide sequence with (i) a polymerase; (ii) a first template nucleic acid comprising (a) a first template recognition region at the 3' end that is complementary or substantially complementary to the 3' end of the first strand of the target nucleotide sequence, (b) a nicking enzyme binding site and a nicking site upstream of the recognition region and (c) a stabilizing region upstream of said nicking site; (iii) a second template nucleic acid comprising (a) a second template recognition region at the 3' end that is complementary or substantially complementary to the 3' end of the complement of the first strand of the target nucleotide sequence, (b) a nicking enzyme binding site and a nicking site upstream of the recognition region and (c) a stabilizing region upstream of said nicking site; and (iv) one or more nicking enzymes that are capable of nicking at the nicking site of said first and said second template nucleic acids, wherein either one nicking enzyme is capable of nicking both of said templates, or each template is capable of being nicked by at least one of the nicking enzymes, and wherein said one or more nicking enzymes do not nick within said target sequence; in an amplification reaction, under conditions in which the polymerase extends the template nucleic acids, thereby generating extended template nucleic acid amplicons; wherein: the target nucleic acid has not been subjected to an initial heat denaturation step; the target nucleotide sequence is between 20 and 40 nucleotides in length; the target nucleotide sequence comprises from 1 to 5 nucleotides more than the sum of the nucleotides of the first template recognition region and the second template recognition region; and the foregoing steps are conducted under substantially isothermal conditions. combining a target nucleic acid having a target nucleotide sequence with (i) a polymerase; (ii) a first template nucleic acid comprising (a) a first template recognition region at the 3' end that is complementary or substantially complementary to the 3' end of the first strand of the target nucleotide sequence, (b) a nicking enzyme binding site and a nicking site upstream of the recognition region and (c) a stabilizing region upstream of said nicking site; (iii) a second template nucleic acid comprising (a) a second template recognition region at the 3' end that is complementary or substantially complementary to the 3' end of the complement of the first strand of the target nucleotide sequence, (b) a nicking enzyme binding site and a nicking site upstream of the recognition region and (c) a stabilizing region upstream of said nicking site; and (iv) one or more nicking enzymes that are capable of nicking at the nicking site of said first and said second template nucleic acids, wherein either one nicking enzyme is capable of nicking both of said templates, or each template is capable of being nicked by at least one of the nicking enzymes, and wherein said one or more nicking enzymes do not nick within said target sequence; (i) a polymerase; (ii) a first template nucleic acid comprising (a) a first template recognition region at the 3' end that is complementary or substantially complementary to the 3' end of the first strand of the target nucleotide sequence, (b) a nicking enzyme binding site and a nicking site upstream of the recognition region and (c) a stabilizing region upstream of said nicking site; (iii) a second template nucleic acid comprising (a) a second template recognition region at the 3' end that is complementary or substantially complementary to the 3' end of the complement of the first strand of the target nucleotide sequence, (b) a nicking enzyme binding site and a nicking site upstream of the recognition region and (c) a stabilizing region upstream of said nicking site; and (iv) one or more nicking enzymes that are capable of nicking at the nicking site of said first and said second template nucleic acids, wherein either one nicking enzyme is capable of nicking both of said templates, or each template is capable of being nicked by at least one of the nicking enzymes, and wherein said one or more nicking enzymes do not nick within said target sequence; in an amplification reaction, under conditions in which the polymerase extends the template nucleic acids, thereby generating extended template nucleic acid amplicons; wherein: the target nucleic acid has not been subjected to an initial heat denaturation step; the target nucleotide sequence is between 20 and 40 nucleotides in length; the target nucleotide sequence comprises from 1 to 5 nucleotides more than the sum of the nucleotides of the first template recognition region and the second template recognition region; and the foregoing steps are conducted under substantially isothermal conditions. the target nucleic acid has not been subjected to an initial heat denaturation step; the target nucleotide sequence is between 20 and 40 nucleotides in length; the target nucleotide sequence comprises from 1 to 5 nucleotides more than the sum of the nucleotides of the first template recognition region and the second template recognition region; and the foregoing steps are conducted under substantially isothermal conditions.