Low-frequency Raman spectra of even and odd n-alcohols have been recorded. The longitudinal acoustic modes (LAM) are described, and the effects of hydrogen-bonding, chain length, and temperature on the frequencies of these vibrations are discussed. The frequencies of the LAMs are interpreted in terms of the one-dimensional crystal model of Minoni and Zerbi and also ab initio calculations on isolated single chains. The low-frequency LAM-1 mode of the hydrogen-bonded dimer exhibited an odd-even effect, and to gain insight into this, the crystal structures of the C-17 and C-20 alcohols were determined by single-crystal X-ray diffractometry. C17H35OH packs in the beta form, with half the oxygen atoms trans and half gauche, with respect to the alkyl chains. C20H41OH adopts an all trans conformation and the packing is in the gamma form. The hydrogen-bonding interactions differ in the two structures. We therefore ascribe the odd-even effect in the LAM-1 frequencies to an odd-even effect in crystal structure.