Several biological effects resulting from exposure to millimeter waves have been reported. In an attempt to determine if millimeter waves might affect the conformational state of membranes, sonicated liposomes have been irradiated with millimeter waves at 41.650 GHz, stabilized in frequency to ±50 Hz. Raman spectra from the lipid vesicles were then collected in the conformational and in the C‐H stretching region. No changes in either the Raman peak locations or relative intensities were detected upon millimeter‐wave irradiation, either below or above the transition temperature of the phospholipid (41 °C).