The ethanolic extract of the adductor muscle of fan-mussel, Atrina pectinata, was fractionated on Dowex 50W-X12 column. Of 19 Dragendorff-positive substances detected, 10 quaternary ammonium bases were isolated and identifted as atrinine, carnitine, β-alanine betaine, glycine betaine, choline, γ-butyrobetaine, trimethylamine oxide, setachydrine, homarine, and trigonelline by comparing mp, IR, UV, MS, and behaviors in TLC with those of the authentic compounds.