The thermotropic liquid crystalline behaviors of ethylcellulose (EC) were investigated by DSC, polarizing microscope with hot stage, and capillary rheometer. It was found that only those EC that have the ethoxyl content over 45% can exhibit the thermotropic liquid crystalline behaviors: the DSC trace showed the transition from mesophase to isotropic phase, the texture appeared under the crossed polarizer, and the rheological flow curves exhibited two yield points.