Depletion of abundant uninformative sequences

A method of preparing a cDNA library, the method comprising:

• (i) providing RNA obtained from a sample, said RNA comprising a targeted subset of RNA sequences and a non-target subset of RNA sequences;
• (ii) providing a first set of primers, wherein primers of the first set of primers are specific for the non-target subset of RNA sequences;
• providing a second set of primers, wherein primers of the second set of primers are random primers or target-specific primers for the target subset of RNA wherein said second set of primers comprise a 5′ RNA tag,
• (iii) transcribing the RNA into cDNA using the first and second set of primers;
• (iv) selectively amplifying the cDNA transcribed from the targeted subset of RNA using the second set of primers thereby generating a cDNA library comprising amplicons from only said target subset of RNA, wherein the selectively amplifying step comprises amplifying the cDNA using an amplification primer targeting the 5′ tag or its compliment, wherein the amplification primer is a DNA/RNA chimeric primer,
• wherein generating the cDNA library comprising amplicons from only said target subset of RNA does not include subtractive hybridization or enzymatic degradation of cDNA transcribed using the first set of primers.