Recent breakthroughs in the high-resolution structural elucidation of ion channels and transporters are prompting a growing interest in methods for characterizing integral membrane proteins. These methods are proving extremely valuable in facilitating the production of X-ray diffraction-grade crystals. Here we present a robust and straightforward mass spectrometric procedure that utilizes matrix-assisted laser desorption/ionization to analyze integral membrane proteins in the presence of detergents. The utility of this method is illustrated with examples of high-quality mass spectral data obtained from membrane proteins for which atomic resolution structural studies are ongoing.