A method and apparatus are described which provide sensitive and repeatable measurements of the saturation magnetostriction &lgr;sof thin ferromagnetic films. The use of magnetoresistance provides a simple, compact method of observing magnetoelastic effects of strain on the film magnetization process. The applicable equations for the technique are presented with the result that &lgr;sis shown to be directly proportional to an easily measured current and inversely proportional to the deflection of the center of the film substrate during bending. Measurements have been made on films ranging from 100 to 2000 Å thick.