Generating a rigorous, description of the effective permittivity of anisotropic media requires an appropriate consideration of its microstructural geometry and orientation. In this study, we use anisotropic geometrical models made of filaments along with electromagnetic wave propagation calculations to investigate the effect of filament orientation on the effective permittivity. As a result, we have identified a correlation tensor parameter that, in conjunction with the filament orientation tensor provides efficient and reliable estimates of the effective permittivity of filamentary structures with solid volume fractions below 10 %.