Long-chain bases were liberated from a crude mixture of sphingolipids from whole tissue of the fresh-water bivalve C. sandai, and conversion of the bases into N-acetyl-0-trimethylsily derivatives was accomplished. The derivatized bases were analyzed by combined gas-liquid chromatography and mass spectrometry. A portion of the sphingolipids was subjected to catalytic hydrogenation from whch saturated long-chain bases (sphinganines) were obtained. The saturated bases were oxidized with lead tetra-acetate and the aldehydes produced were analyzed by gas-liquid chromatography. The aldehydes were further oxidized to acids with silver oxide, the resulting fatty acids methylated and also analyzed by gas-liquid chromatography. By these analyses, altogether five long-chain bases were identified, consisting of hexadeca-4-sphingenine (15%), heptadeca-4-sphingenine (2%), iso-octadeca-4-sphingenine (13%), octadeca-4-sphingenine (39%) and anteiso-noadeca-4-sphingenine (31%). So far no branches have been found in shellfish spingolipid long-chain bases.