In the past few years, interest has drastically increased in using surgically inserted electrodes to ablate cancer cells. The treatment is referred to as irreversible electroporation (IRE) and has the advantage of being a minimally invasive procedure that can be used to treat tumors while minimizing damage to surrounding tissue and preserving blood vessels. However, treatment planning is required to ensure the electrodes are placed in the correct location and at the proper voltages to ensure all cancer cells are killed while causing the least amount of damage to healthy cells. Computer simulations are used to develop individual treatment plans. Currently, computer simulations for treatment planning have used an isotropic conductivity that increased as the tissue was electroporated. In this work, we propose using a conductivity tensor in which the conductivity increases more in the direction of the electrical field, and results in an anisotropic conductivity tensor. This slightly alters the predicted ablation zone, and could lead to more accurate simulations.