To characterize the degree of similarity inherent to parameters of the optically uniaxial birefringent protein-fibril networks of biological tissues, a new parameter — complex degree of mutual anisotropy — has been offered. The technique of polarization measuring the coordinate distributions of the complex degree of mutual anisotropy of biological tissues has been developed. It has been shown that statistical approach to the analysis of complex degree of mutual anisotropy distributions for biological tissues in various morphological and physiological states and for different optical thicknesses appears to be more sensitive and efficient in differentiation of physiological state, as compared to investigations of complex degree of mutual polarization in the corresponding laser images.