The purpose of this project is to model a novel and promising cancer treatment that involves the destruction of tumor cells by the direct injection of biocompatible nanoparticles (gold-silicon nanoshells) and their subsequent heating with near-infrared radiation. The use of near infra-red radiation gives this procedure an advantage over other thermal ablation treatments for cancer since light at this range (700-900 nm) is not significantly absorbed by chromopores in human tissue and can therefore penetrate more deeply (Hirsch et al., 2003). The method is also quick and minimally invasive. Using the simulation software FIDAP, we analyzed the diffusion of the nanoshells into a spherical tumor after being injected into its center. The change in temperature of the tumor due to the exposure of the nanoshells to near-infrared light was also studied. We found out that when 50 microliters of nanoshell solution (concentration of 1.5 e10 nanoshells/ml) is introduced to a 1-cm diameter tumor, it takes 29 hours for the nanoshells to fill up the tumor. At this point, exposure of the tumor with a laser (800 nm, power = 5.6 W/m2) for 10 min raised the temperature of the entire tumor to at least 45?C, effectively destroying it. Further analysis on the effect of nanoshell distribution on the temperatures obtained showed that it has negligible effect. All distributions tested (0%, 25%, 50%, 75% and 100%) resulted in the entire tumor being heated above 45?C. The laser can therefore be immediately applied to the tumor right after injection. Nanoshell concentration vs. time and temperature vs. time profiles for the tumor for various treatment conditions were also obtained. The results of the mathematical modeling will help further studies of this treatment. Although the method still needs to be refined, it should provide an effective new treatment for the destruction of breast carcinomas and other localized tumors.