A method for detecting or amplifying a miRNA target nucleotide, of between 18 to 25 nucleotides in length, in a sample, preferably a human biological sample, performed in a one-step approach combining the reverse transcription and subsequent polymerase chain reaction in a single tube and buffer, wherein the method comprises: a. carrying-out a retro-transcription reaction by using a bivalent primer that acts as a forward primer for the conservative step of retro-transcription of the miRNA target nucleotide and forms a first strand cDNA product from the said miRNA target nucleotide; and b. carrying-out a polymerase chain reaction by using a forward primer that hybridizes with the first strand cDNA product which is then extended to form a second cDNA strand product; wherein then the bivalent primer then continues the amplification reaction over the second strand product acting as a reverse primer for the polymerase chain reaction; wherein the bivalent primer comprises a first sequence of a given base length complementary to one primer portion of the miRNA target nucleotide that serves directly as the template upon which the primer can anneal and to one primer portion of the second strand or cDNA product that serves directly as the template upon which the primer can anneal; and a second sequence of a given base length provided adjacent to the side of 3'terminus of said first sequence which is non-complementary with the cDNA products and allows end-tagging the amplicon(s) obtained, and wherein the method is further characterized in that a detection probe of from 13 to 21 nucleotides in length is used for detecting the amplified products of the PCR reaction, and wherein said probe is further characterized in that said probe is 100% complementary to a portion of the target miRNA sequence, and wherein said complementarity overlaps in one, two or three nucleotides with the primer portion of the cDNA product that serves directly, or by virtue of its complement, as the template upon which the bivalent primer or the forward primer anneal, and wherein the DNA polymerase used for carrying-out the polymerase chain reaction possesses a 3'->5' exonuclease activity. a. carrying-out a retro-transcription reaction by using a bivalent primer that acts as a forward primer for the conservative step of retro-transcription of the miRNA target nucleotide and forms a first strand cDNA product from the said miRNA target nucleotide; and b. carrying-out a polymerase chain reaction by using a forward primer that hybridizes with the first strand cDNA product which is then extended to form a second cDNA strand product; wherein then the bivalent primer then continues the amplification reaction over the second strand product acting as a reverse primer for the polymerase chain reaction; wherein the bivalent primer comprises a first sequence of a given base length complementary to one primer portion of the miRNA target nucleotide that serves directly as the template upon which the primer can anneal and to one primer portion of the second strand or cDNA product that serves directly as the template upon which the primer can anneal; and a second sequence of a given base length provided adjacent to the side of 3'terminus of said first sequence which is non-complementary with the cDNA products and allows end-tagging the amplicon(s) obtained, and wherein the method is further characterized in that a detection probe of from 13 to 21 nucleotides in length is used for detecting the amplified products of the PCR reaction, and wherein said probe is further characterized in that said probe is 100% complementary to a portion of the target miRNA sequence, and wherein said complementarity overlaps in one, two or three nucleotides with the primer portion of the cDNA product that serves directly, or by virtue of its complement, as the template upon which the bivalent primer or the forward primer anneal, and wherein the DNA polymerase used for carrying-out the polymerase chain reaction possesses a 3'->5' exonuclease activity. wherein the bivalent primer comprises a first sequence of a given base length complementary to one primer portion of the miRNA target nucleotide that serves directly as the template upon which the primer can anneal and to one primer portion of the second strand or cDNA product that serves directly as the template upon which the primer can anneal; and a second sequence of a given base length provided adjacent to the side of 3'terminus of said first sequence which is non-complementary with the cDNA products and allows end-tagging the amplicon(s) obtained, and wherein the method is further characterized in that a detection probe of from 13 to 21 nucleotides in length is used for detecting the amplified products of the PCR reaction, and wherein said probe is further characterized in that said probe is 100% complementary to a portion of the target miRNA sequence, and wherein said complementarity overlaps in one, two or three nucleotides with the primer portion of the cDNA product that serves directly, or by virtue of its complement, as the template upon which the bivalent primer or the forward primer anneal, and wherein the DNA polymerase used for carrying-out the polymerase chain reaction possesses a 3'->5' exonuclease activity.