Recently, hyperthermia has been investigated as an alternate therapy for the treatment of tumors. The present project explored the feasibility of preferential hyperthermia as a method of treating deep seated tumors. The overall goal of this research was to determine theoretically if preferential heating could be used to attain the desired thermal dose (DTD) for a two cm diameter tumor. The simulations in this work show that, when using a single silicon carbide insert, the model cannot provide enough energy for an entire 2 cm diameter tumor to receive the DTD. However, when using an enhanced design model with multiple (4) silicon carbide inserts, the DTD could be attained in a tumor up to 3.5 cm in diameter. This study involved using the commercially available software package ANSYS 7.0 program to model a spherical 2 cm tumor, assuming the tumor is located in deep tissue with a constant perfusion rate and no major blood vessels nearby. This tumor was placed in the center of a cube of healthy tissue. To achieve the preferential heating of the tumor, a silicon carbide insert was placed in the center of the tumor and microwave energy was applied to the insert (in the form of volumetric heating). The thermal modeling of this system was based on the Pennes Bioheat equation with a maximum temperature limitation of of 80 ºC. The Thermal Dose Analyzer software program was used to evaluate the results of the thermal simulations (from ANSYS) to determine if the DTD had been attained. Additional enhanced design models were also examined. These models include 2 cm and 4 cm tumors with four silicon carbide inserts symmetrically placed about the tumor and a 4 cm tumor model using a single silicon carbide insert with antennae attached to the insert to increase energy distribution to the tumor. The simulations show that only the enhanced design cases with four silicon carbide inserts can achieve the DTD for an entire 2 cm tumor. / Master of Science