Plants are incapable of escaping from a changing environment. Therefore, they have developed sophisticated mechanisms for acclimation and survival under unfavorable conditions, such as unfavorable temperatures. Low temperatures induce a number of alterations in cellular components, including the extent of fatty acid unsaturation (Cossins, 1994), the composition of glycerolipids (Lynch and Thompson, 1982), the positional redistribution of saturated and unsaturated fatty acids within lipid molecules (Thompson and Nozawa, 1984), changes in the protein composition (Raison, 1973; Tiku et al., 1996), and activation of ion channels (Knight et al., 1996). Low temperatures activate a number of cold-inducible genes (Jones and Inouye, 1994), such as those that encode dehydrins, lipid transfer proteins, translation elongation factors, and the late-embryogenesis-abundant proteins (for refs., see Nishida and Murata, 1996). Despite extensive research on the mechanisms that regulate the expression of such temperature-induced genes, little is known about the primary sensor that detects a change in temperature or about the transducers of the temperature signal. In this Update, we focus on the role of biological membranes in the perception of cold temperatures and the subsequent signal transduction.