Gramicidin A' is believed to form transmembrane channels in lipid bilayers and biological membranes. The first Raman spectroscopic study of gramicidin A' is presented. Evidence is found for two types of conformation. One type is found in the powder and has a Raman spectrum similar to that of model polypeptides with beta hydrogen bonding. The second type is found when gramicidin A' is dissolved in dimethyl sulfoxide.