The thermodynamic models available in the literature predict that during self-organizing processes the entropy of a cell considered as an open thermodynamic system decreases. This prediction leads to conclusion that cell imports a certain amount of negative entropy and generates entropy during irreversible metabolic processes. The controversial concept of negentropy was criticized recently. In this research a new model was proposed that isn’t based on the steady state approximation and describes living systems more realistically. The analysis of the suggested model of an open thermodynamic system far from equilibrium, led to the conclusion that the entropy during self-organizing processes increases during growth (of a molecule or a cell). Using as models the synthesis of an oligopeptide and a growing hydrocarbon chain, it was shown that entropy of an open thermodynamic system increases during addition of monomers (a self-organizing process). A derived equation confirms the results obtained by calculations with literature experimental values of molar entropy. The decrease of entropy observed in self-organizing processes occurred only during phase transition.