The composition of fatty acids in the tissue of hearts of striped bassMorone saxatiliswas determined by a chemometric method, consisting of methanolysis of the tissue, gas chromatography of the resulting fatty acid methyl esters, and multivariate statistical treatment of the analytical data. Striped bass from spawning stocks in the Hudson River, the Roanoke River, and the Chesapeake Bay area had significantly different profiles of 13 selected fatty acids, although the spread among individuals within stocks was considerable, In a training set of 49 striped bass, all were correctly classified; in a test set of 19 samples, 84% were assigned to the correct stock.