The absorption and emission of vibrational quanta by the conduction electrons in metals leads to a contribution π²νFσ/K₀(10^-3) to the internal friction per cycle independent of frequency. This holds only for longitudinal vibrations whose wavelength is sufficiently small compared with the dimensions of the sample. In the above ν is the number of free electrons per atom; σ/K₀ is twice the ratio of the velocity of sound to that of the fastest electron and is of the order 10^-3. F is a constant of the order unity; its exact value can be found from the temperature coefficient of the electrical resistivity at high temperatures.