We use the matrix formalism to investigate a liquid-crystal system containing impurities. As an example, we calculate correlation functions for fluctuations of the director orientation and of the order parameter, which characterizes an isotropic subsystem.We previously proposed a formal method for analyzing the correlation behavior of liquid systems containing a large number of components [1]. Such a method can be extended with minimal changes to the case where the liquid is characterized by a vector order parameter. The most instructive example of such a system is a liquid-crystal system. It is known that a liquid crystal in the nematic phase is characterized by a unit vector-director that indicates the direction of the preferred orientation of the long axes of the liquid crystal molecules. Although the nematic liquid-crystal order parameter is a tensor quantity, when investigating small deviations of the director from the equilibrium homogeneous distribution, we can take the vector of small fluctuations of the director as the order parameter, and the system can therefore be described by a vector order parameter. We consider such a system, liquid in the isotropic phase, in the presence of impurities. We assume that the liquid crystal and isotropic impurities constitute two interacting subsystems respectively characterized by the director and by the deviation of the density from the mean.The energy of deformation due to inhomogeneities in the director distribution in the nematic liquid crystal is known to be [2]where K ii , i = 1, 2, 3, are the Franck moduli and n( r ) is the unit vector-director.If a system is placed in an external field (we assume that it is a magnetic field for definiteness), we must also take the interaction with this field into account. The energy of interaction of a liquid-crystal system with the magnetic field H iswhere χ a is the anisotropy of magnetic susceptibility. For the isotropic subsystem, the free energy depends on the profile of the scalar order parameter φ( r ), which we choose to be a local density of the isotropic phase. The free energy of the isotropic subsystem is then [3]