Noninvasive assessment of cardiac function during daily activities is desired in many facets of research. To accomplish this, a personal monitor was developed that combines electrocardiography, impedance cardiography, signal processing , and data storage in a wearable and untethered unit. The authors evaluated the system performance under a variety of activities and conditions. It was found that the personal cardiac bioimpedance monitor provided useful cardiac surveillance in a varied subject population during controlled and uncontrolled activities and in a variety of environments.<<ETX>>