The dynamics of lipid composition of two kinds of blue-green algae having different temperature optima of growing was studied as affected by low temperature. It is shown that a decrease of temperature inhibited accumulation of GL and chlorophyll in the both species and in the future the HL content increased in A. cylindrica at 10-12-degrees-C and in S. platensis at 25-27-degrees-C and decreased in S. platensis at 10-12-degrees-C. Phospholipid content increased in the both algae species under temperature drop. It is concluded that the specificity of reaction to the low temperature is, apparently, due to the peculiarities of photosynthetic apparatus and programmed by the species peculiarities manifested in temperature optimum and probabilistic possibilites of its variations.