RNAcan be extracted from cultured cells, peripheral blood, bone marrow, plasma, serum, body fluids, and fresh or frozen tissues. RNA can also be extracted from formalin-fixed paraffin-embedded (FFPE) tissues. Methods for RNA extraction can be divided into three groups: phenol/chloroform extraction, silica spin-column absorption, and isopycnic gradient centrifugation. Two differentRNAisolation procedures are described in this unit. The first basic protocol describes a one-step isolation involving monophasic lysis with guanidine isothiocyanate and phenol followed by chloroform extraction. The second basic protocol describes a silica-column separation method for RNA isolation. © 2013 by John Wiley & Sons, Inc.