We present a measurement system for magnetic position and orientation tracking. It uses a rotating magnet as transmitter and a three-axis magnetic field sensor to measure the magnetic field ellipse produced by the magnet. A theory is given for the calculation of the magnet’s position and orientation from the ellipse’s semi-axis components. Detection range and accuracy of the tracking method and their dependence on magnetic moment, noise levels of the environment and the sensor type are shown. With the use of two moderately distant identical sensors and an adequate evaluation of the tracking components’ evolution, various unique features of the new method can be gained. Perturbation of single tracking results by external disturbances will be flagged-up and – most important – the right one out of four possible solutions as delivered by the tracking algorithm can be reliably chosen, independent of the tracking course. This way, a unique solution of the three-dimensional inverse problem can be achieved.