The invention relates to methods for the amplification of ribonucleic acids, comprising the following steps: (a) a single stranded
DNA is produced from an
RNA by means of reverse transcription, using a single-stranded primer having a defined sequence, an
RNA-dependent
DNA polymerase and
deoxyribonucleoside triphosphates; (b) the template
RNA is removed; (c)
a DNA duplex is produced by means of a single-stranded primer comprising a box sequence,
a DNA polymerase and
deoxyribonucleoside triphosphates; (d) the duplex is separated into single-stranded DNAs; (e)
DNA duplexes are produced from one of the single-stranded DNAs obtained in step (d) by means of a single-stranded primer comprising a
promoter sequence at its 5′end and the same defined sequence as the primer used in step (a) at its 3′end,
a DNA polymerase and
deoxyribonucleoside triphosphates; (f) a plurality of RNA single strands, both ends of which comprise defined sequences, are produced by means of an
RNA polymerase and
ribonucleoside triphosphates. The invention also relates to kits for amplifying ribonucleic acids according to one of said methods, said kits comprising the following components: (a) at least at least one single-stranded primer, which contains a
promoter sequence; (b) at least one single-stranded primer comprising a box sequence; (c) an RNA-dependent
DNA polymerase; (d) deoxyribonucleoside triphosphates; (e) a DNA-dependent
DNA polymerase; (f) an
RNA polymerase; and (g)
ribonucleoside triphosphates.