In this paper a simple model for study of molecular orientation in polycrystalline polymers is introduced. The idea of the six-phase model resides in virtual division of the two phases (crystalline and noncrystalline) into three parts oriented in orthogonal directions. Some important parameters of the anisotropy such as the orientation function, normalized optical anisotropy parameter, birefringence and sonic modulus are discussed. It is shown that all relations usually used for description of anisotropy of polycrystalline polymers can be easily derived from the six-phase model.