CA-125 and carcinoembryonic antigen (CEA) are two biomarkers present in blood that can indicate the presence of ovarian cancer. They can also be used, both in conjunction with each other and independently, to determine the effectiveness of the treatment being meted for the disease. A label-free multiplexed interdigitated electrode array (IDEA) immunosensor was developed to detect both CA-125 and CEA in buffer solution at levels typically seen in patients with ovarian cancer . Electrochemical impedance spectroscopy was used to measure the increase in impedance when a binding event occurred between the target antigen and its specific antibody that was anchored to the surface of an interdigitated electrode array. CA-125 was detected in concentrations as low as 10units/mL and as high as 80units/mL. CEA was detected in concentrations as low as 1pg/mL and as high as 10μg/mL.