  We study the effects of anisotropy on the magnetoresistance of Weyl
semimetals (WSMs) in the ultraquantum regime. We utilize the fact that many
Weyl semimetals are approximately axially anisotropic. We find that anisotropy
manifests itself in the strong dependence of the magnetoresistance on the polar
and azimuthal angles determining the orientation of the anisotropy axis with
respect to the applied magnetic field and electric current. We also predict
that the ratio of magnetoresistances in the geometries, where the magnetic
field and anisotropy axes are aligned and where they are orthogonal, scales as
$(v_\bot/v_\parallel)^2$ where $v_\bot$ and $v_\parallel$ are the corresponding
Fermi velocities.
