The modulated magnetic signature based method has been recently suggested for non-invasive detection of blood pulse. Here we present our experience with the use of a Giant Magnetic Resistance (GMR) based sensor for non-invasive detection of a bio-rhythm. The influence of the biasing magnetic field on the amplitude and shape of the detected signal is presented. Guidelines for the design of a bio-medical transducer using the principle are also provided. The detected biorhythm is compared to other bio signals such as the blood flow velocity and arterial distension to gain insight into the physiological significance of the detected signal. The analysis shows that the magnetic sensor provides a signal that is strongly correlated to the blood volume in the neighbourhood of the sensor. Finally, the possibility of using the GMR based sensor for estimation of arterial compliance is investigated. Simultaneous measurements performed at two different sites on the body show that this sensor can be used to measure arterial pulse wave velocity which is a clinically accepted measure of global arterial stiffness. © 2010 IEEE.