The characterization of rare messages in cDNA libraries is complicated by the substantial variations that exist in the abundance levels of different transcripts in cells and tissues. The equalization (normalization) of cDNA is a helpful approach for decreasing the prevalence of abundant transcripts, thereby facilitating the assessment of rare transcripts. This unit provides a method for duplex-specific nuclease (DSN)based normalization, which allows for the fast and reliable equalization of cDNA, thereby facilitating the generation of normalized, full-length-enriched cDNA libraries, and enabling efficient RNA analyses. Curr. Protoc. Mol. Biol. 90:5.12.1-5.12.27. © 2010 John Wiley & Sons, Inc.