This is an in vitro study of photodynamic therapy (PDT) in the MG-63 line of human osteosarcoma cells, as mediated by aminolevulinic acid (ALA). The primary goal of this work is to determine the feasibility and effectiveness of treating osteosarcoma through PDT. In addition, this work is aimed at determining whether the resulting cell death occurs through apoptosis or cellular necrosis. The MG-63 cells are treated with increasing concentrations of ALA from 0.1-10 mM ALA, leading to the accumulation of the photosensitizer protoporphyrin IX (PpIX) within the cells. After incubation periods of 4 and 24 hours in ALA, the cells are illuminated by 0-10 J/cm2 of 636 nm light in order to activate the PpIX and induce oxidative damage to the cells. Light is administered by an 8x12 array of LED's, which are controlled by an Arduino Duemilanove microcontroller board in order to assure ease of use along with accurate levels of exposure. Controls for this experiment include 0 J/cm 2 of light exposure for all experimental concentrations of ALA, as well as illuminating cells that have not been incubated in ALA at all experimental levels of illumination. MG-63 cells are analyzed through fluorimetry and MTT assays in order to determine the effectiveness of ALA mediated PDT of osteosarcoma.