Total RNA was isolated from human leukocytes (monocytes, granulocytes), various cell lines (COS-7, Mono-Mac-6, L-132, HaCaT, EA.hy926, HL-60), and fungal mycelium by a rapid two-step method. Cells were lysed with NaDodSO4 in a citric acid-containing buffer. This procedure was succeeded by salt precipitation to remove contaminating DNA and protein and a final alcohol precipitation of RNA. Isolated RNA was of high quality, with a reasonable yield and little or no protein or DNA contamination. We present here a fast method for preparing RNA particularly from cell lines, which limits the use of toxic compounds.