The internal structure of a sheared assembly of monodisperse ellipsoids is investigated using three-dimensional Voronoi analysis. The discrete element method is employed to simulate isotropic and triaxial compression tests of ellipsoidal particles. A recently developed Voronoi tessellation technique, i.e., Set Voronoi tessellation, is applied to constructing Voronoi cells of assemblies at a series of shearing states. Several quantities are provided to quantify the properties of Voronoi cells, including local porosity, reduced surface area, sphericity, and a modified Minkowski tensor. We show that average local porosity, average reduced surface area, and average sphericity are functions of global porosity and mean coordination number during shearing, suggesting a relationship between void and particle networks. Moreover, local porosity and reduced surface area statistically comply with a modified lognormal distribution regardless of particle shape for a similar global porosity. However, the shape of a Voronoi cell is significantly dependent on the particle it encloses. Shear-induced inhomogeneity and anisotropy measured by Voronoi-based quantities are also examined. Increasing shear-induced entropy is observed, which means a more disordered void network during shearing. Furthermore, anisotropy of Voronoi cell orientations shows a comparable trend with anisotropy of contact normals. These findings are useful for developing a better understanding of void networks and their relationship with particle networks for non-spherical assemblies. (C) 2017 Elsevier B.V. All rights reserved.