Dielectrostriction is a rheo-dielectric phenomenon that relates the variation of dielectric properties of a material to deformation. For an initially isotropic material, two independent material parameters, called the strain-dielectric coefficients, alpha(1) and alpha(2), are required to describe dielectrostriction in terms of strain. Deformation affects a material's dielectric properties in two ways: (a) by introducing anisotropy in the material, which is characterized by alpha(1), and (b) by changing the volume density of the polarizable species, which is associated with (1/3 alpha(1)+alpha(2)). Purely viscous fluids remain isotropic during any flow-induced deformation, and therefore the coefficient alpha(1) is always zero. In this paper, the dielectrostriction effect is studied in viscoelastic materials that are formulated to possess different degrees of elasticity. A special planar capacitance sensor rosette was employed to measure the coefficients alpha(1) and alpha(2) for these viscoelastic materials. The relationship between the material's elasticity and the coefficient alpha(1) is discussed, together with some potential applications based on this relationship in the conclusion. (C) 2011 The Society of Rheology. [DOI: 10.1122/1.3539654]