Seasonal variation in proximate, amino acid and fatty acid composition of the body wall of sea cucumber Apostichopus japonicus was evaluated. The proximate composition, except for ash content, changed significantly among seasons （P〈0.05）. Alanine, glycine, glutamic acid and asparagic acid were the most abundant amino acids. Total amino acid and essential amino acid contents both varied clearly with seasons （P〈0.05）. 16：0 and 16：1n7 were the primary saturated fatty acid （SFA） and monounsaturated fatty acid （MUFA） respectively for all months. EPA （20：5n-3）, AA （20：4n-6） and DHA （22：6n-3） were the major polyunsaturated fatty acids （PUFA）. The proportions of SFA and PUFA yielded significant seasonal variations （P〈0.001）, but MUFA did not changed significantly. The results indicated that the biochemical compositions of the body wall in A. japonieus were significantly influenced by seasons and that the body wall tissue is an excellent source of protein, MUFA and n-3 PUFA for humans.
