Laser Interstitial ThermoTherapy (LITT) is a well establish surgical method used in the treatment of tumors. This study analyzes the extent of tissue damage when using LITT in a liver. GAMBIT and FIDAP was used to model a spherical tumor with a diameter of 4cm in a 12cm spherical liver. The mesh that was used contained 14326 nodes which were shown to converge using our mesh convergence analysis. From our sensitivity analysis, the optimal time the laser would be on was determined to be 40 seconds, because this was the time where most of the cancerous tissue was destroyed while keeping healthy tissue damage at a minimum. The optimal laser power was determined to be 30W, which provided the correct amount of heating needed to induce necrosis in the most of the tumor, and maintain a safe temperature below 40oC for healthy liver tissue. However, there a small amount of healthy liver was destroyed, but this could not be avoided due to the cylindrical geometry of the laser applicator. In our sensitivity analysis, we determined that varying the thermal conductivity caused very little change in the average tumor temperature. This indicates that thermal conductivity parameter is relatively insensitive to changes and using our values for thermal conductivity would accurately model the process.