Abstract: A non-invasive diagnostic physiological monitoring system for mammals, particularly humans is disclosed. The system includes: at least two surface contact electrodes; means for holding the electrodes in contact with an exterior surface of a mammal; means for pairing the electrodes; an electronic block coupled to at least one of the pairings wherein the block includes a transmitter for transmitting a predetermined electrical signal to a first pair of electrodes in the pairing, a and detector for detecting electrical impedance characteristics on the first pair of electrodes or on a second pair of electrodes in the pairing; and a signal processor coupled to the detector wherein the electrical impedance characteristics are divided into at least two groups by frequency.