The contents of fat and fatty acids in Callista erycina (Linnaeus), Paphia (Paratapes) undulata (Born), Meretrix meretrix (Linnaeus), Chlamys farreri (Jones et Preston) and Patinopecten yessoensis (Jay) were studied. Fat was extracted with Bligh & Dyer (B&D) method. The lipid classes were transesterified with potassium hydroxide in methanol. Fatty acid methyl esters (FAMEs) were assayed with GC-MS and polar capillary column (HP-INNOWax 30 m x 0.25 mm i.d. x 0.25 micron). GC injector temperature was 220 degrees C. The column temperature was programmed from 150 degrees C (1 min) to 200 degrees C at 10 degrees C/min and then from 200 degrees C to 250 degrees C at 2 degrees C/min. FAMEs were identified by MS library, and part by their standards. Total identified fatty acids were over 99% for all samples. Fat contents of them were all over 1% by wet samples. And ratios between omega-3PUFA and omega-6PUFA were above 2 by and large. Patinopecten yessoensis (Jay) contains more fat and the valuable fatty acids, EPA and DHA. It is suitable to use it as the source of EPA and DHA.