The effect of bond-length alternation on the main features of the Raman vibrational spectra of polyacetylene is examined. It is shown that the semiempirical potential energy surfaces for cyclic polyene models, which display the bond-length alternating equilibrium geometry, yield vibrational frequencies that are in reasonable agreement with observed principal Raman bands. However, these frequencies are rather insensitive to the details of the potential energy surface employed, thus explaining the controversy between earlier computations (Ovchinnikov et al.) and the experimental evidence of bond-length alternation in all-trans polyacetylene (Fincher, Jr., et al.). Nevertheless, the normal mode character of these vibrations qualitatively changes with the introduction of the bond-length alternation.