Acoustic spectra have been investigated for a series of poly(ethylene glycols) (PEGs) with molecular masses of 200, 400, and 600. Velocity of sound propagation c and sound attenuation alpha f(-2) were measured in the frequency interval from 5 to 2500 MHz and temperature interval from 278 to 343 K. The acoustic spectra of PEGs in the frequency range studied comprise two simple dispersion regions. Characteristic parameters for these regions were calculated. Possible molecular mechanisms of the processes responsible for the regions are considered. It turns out that the low-frequency dispersion region is caused by conformational restructuring processes in PEG molecules. The main contribution to the sound attenuation was shown to be caused by rotational isomeric relaxation process of the type trans-trans<->trans-gause. Thermodynamical and kinetic parameters of the low-frequency relaxation region are reported.