Ultrasonic surface waves propagating on a piezoelectric substrate are accompanied by electric fields which can interact with charge carriers in an adjacent medium. This interaction and the resulting attenuation of the elastic surface wave have been measured for different metal films on a quartz single‐crystal substrate. As the films are deposited on the substrate, the resistivity of the films decreases continuously, and it was found that the interaction between the ultrasonic wave and the charge carriers in the film reaches a maximum for a resistivity of the films on the order of 5 M&OHgr;/sq, but the magnitude of the resulting attenuation of the surface wave was dependent on the film material. Values of the maximum attenuation varied between 0.27 dB/cm for bismuth and 2.8 dB/cm for copper at a frequency of 31.5 MHz. A theoretical model was developed which showed good agreement with the experimental results for the materials used.