The concept of the Shannon information in the theory of communication is wellknown. The information is thus connected with entropy which is the most complete measure of degree of uncertainty states at the statistical description of macroscopic objects. In open systems the sequences of nonequilibrivm phase transition are possible. They can lead both to degradation, and to self-organization. In these cases entropy serves as the measure of relative degree of chaoticity states of open systems. In the paper for the first time the definition of information concerning the states of open systems is proposed. The concrete definition of the information for processes in Boltzmann gas, for nonlinear Brownian motion in autoosciilatory systems - generators are presented. The connection of concept of information with the criterion of a relative degree chaoticity - with S-theorem, as well as with definition of Lyapunov functionals for open systems is established. The definition of the information for the medico-biological systems, where one of the main concepts is the «norm of chaoticity», is considered as well.