As a modification and improvement of Slocombe's and O'Driscoll's terpolymerization patterns, a new graphical representation of terpolymer systems has been proposed. The suggested patterns retain all the information necessary to describe ternary systems, including also those related to their azeotropic behavior. The main advantage of the proposed representation is its similarity to the accustomed binary representation: the sides of the composition triangles depict the behavior of the corresponding binary systems.