The effect of alpha-tocopherol on the frequency of the CH2 stretching bands of infrared spectra of dipalmitoylphosphotidylcholine multibilayers has been investigated, both in H2O and 2H2O buffer, to determine the reason for the discrepancy in the literature between the results of different spectroscopic techniques relating to the effect of alpha-tocopherol on membrane order in the gel phase. In contrast to previous FTIR studies, the present FTIR results indicate that alpha T increases the frequencies of the CH2 stretching bands in the gel phase, which implies an increase in the number of gauche conformers (increase in disordering), which is in agreement with other ESR and NMR spectroscopic studies.