Crystalline poly(ethylene glycol)s (PEG) of number-average molar mass 1000, 1500, 2000, and 3000 g mol(-1) and the cyclic analogues were studied by low-frequency laser-Raman spectroscopy and differential scanning calorimetry. The frequencies of the single-node longitudinal acoustic modes (LAM-1) of the rings were higher than those of the corresponding unfolded methoxy-ended chains by a factor of ca. 1.8. Melting points and enthalpies of fusion of the rings were lower than those of unfolded-chain crystals. The structural implications of the results are discussed.