In this paper, the unusual properties of amorphous soft magnetic wire with Fe-based or Co-based in compositions have been discussed: giant magnetoimpedance effect (GMI), giant stress-induced impedance effect, large Barkhausen effect, magnetostriction effect. Sensor operating principles and applications exploiting these unusual properties have also been discussed: magnetic field sensors, position sensors, biosensors, non-destructive testing sensors, stress sensors etc. (c) 2005 Springer Science+ Business Media, Inc.