The dislocation contribution to the ultrasonic attenuation of high‐purity copper single crystals has been quantitatively determined by forming the difference between the measured attenuation and the nondislocation part of attenuation as measured after heavy irradiation. In this way mainly, the influence of temperature, deformation, &ggr; irradiation, and heat treatment on the dislocation damping has been studied. The measurements were evaluated according to the Granato‐Lu¨cke theory of dislocation resonance. One of the main objectives of the work was to test the applicability of various experimental and theoretical methods for gaining quantitative information on dislocations from ultrasonic attenuation measurements.