Total lipid percentage and fatty acid ratios in nuts from Castanea dentata (Marsh) Borkh (American), C sativa Mill (European), C mollissima Bl (Chinese) chestnuts and C pumila (L) Mill (chinkapin) were significantly different among all species and among individuals within species. Total lipids and fatty acids were greatest in American chestnuts followed by chinkapins, then European chestnuts, and lowest in Chinese chestnuts. Palmitic, stearic, oleic, linoleic and linolenic acids comprised the fatty acid complement in all species. Free sugars (fructose, glucose and sucrose) and the sugar-alcohol inositol did not differ significantly (P > 0.05) by species except in the European chestnuts where fructose and glucose were absent. Citric acid was present in all species except the European chestnuts. Malic acid was present in all species except in the American chestnuts. These results can be used to test nuts of new hybrids being bred for nut orchards and for wildlife mast production.