NucleoSpin® RNA kits are recommended for the isolation of RNA from cultured cells and tissue. Support protocols for the isolation of RNA from cell-free biological fluids, bacteria, and yeasts using the NucleoSpin® RNA kit are included. The NucleoSpin® RNA kits allow purification of pure RNA with an A260/A280 ratio generally exceeding 1.9 (measured in TE buffer, pH 7.5). Even biological samples which are sometimes difficult to process will yield high quality RNA. Such samples are, for example, mouse tissue (liver, brain), different tumor cell lines, Streptococci, and Actinobacillus pleuropneumoniae. The isolated RNA is ready to use for applications like reverse transcriptase-PCR (RT-PCR), primer extension, or RNase protection assays.