The RiboMinus™ Human/Mouse Transcriptome Isolation Kit constitutes a novel purification system that enriches the whole spectrum of mRNA species by depleting large ribosomal RNA molecules in a total RNA sample. The kit removes >95% of 18S and 28S rRNA molecules from human or mouse total RNA (Figure 1) without relying on current polyA+ purification methods. This increases the representation of mRNA species, including non-polyA-tailed, fragmented mRNA or other regulatory RNAs that cannot be purified via polyA-selection methods. Purified RNA is suitable for several downstream applications, including, library construction, RT-PCR, and microarray (Figure 2).