The steps for preparing the lysate are different depending on the starting material. Please ensure you follow the correct procedure for your starting material (see the section Disrupting and Homogenizing Starting Materials and the different lysate preparation protocols here). The subsequent steps detailed in Genomic DNA removal and total RNA purification are the same in all cases. This protocol is designed for the isolation of all sizes of RNA (including miRNA) from a wide variety of biofluids such as saliva, urine, semen, CSF and blood. We recommend the use of non-coagulated blood samples (including fresh and anticoagulant treated blood). Follow this protocol for isolating viral RNA from biofluids. See here for isolating total RNA or viral RNA from plasma or serum.