Surface potential of biomedical implants can significantly alter the behavior of the surrounding cells including cell morphology and viability. In this work, the effect of changing the potenial of a CoCr biomedical alloy on the morphology and viability of murine preosteblast cells (MC3T3) was studied. CoCr samples were polarized to cathodic and anodic voltages ranging from -1000 to +500 mv. The morphology and viability were studied using scanning electron microscopy and Live-dead assay techniques, respectively. It was found that voltage significantly influences the cellular response and there exists a voltage viability range, outside of which cells will not be viable. Both anodic (greater than 500 mV) and cathodic (more negative than -100 mV) voltage extremes induced cell death on CoCr surfaces.