Chemical composition in various domestic and foreign commercially grown oysters were examined on 2005 to 2007. Specimens of Crassostrea gigas (Japan, U.S.A., New Zealand and Australia), Crassostrea nippona (Japan), Crassostrea sikamea (U.S.A.), Crassostrea virginica (U.S.A.), Ostrea edulis (U.S.A.) and Ostrea lurida (U.S.A.) were used, and similar shell sizes of them were selected. After stripping the shell, the samples were weighed and homogenized, and then the moisture, zinc (Zn), copper (Cu), iron (Fe), cadmium (Cd), calcium (Ca), magnesium (Mg), (atomic absorption analysis), taurine (HPLC) and glycogen (phenol-sulfuric acid colorimetric method) were determined. In the samples of Crassostrea gigas, differences in the chemical composition were recognized based on the year collected. In specimens from Japan and New Zealand, Zn and Cu concentrations were higher than those in specimens from Australia and U.S.A.. The Cd concentration in oysters from U.S.A. was higher than that in those from Japan and New Zealand. Moisture showed an inverse correlation with taurine. There was a strong correlation between Zn and Cu, but not between Cd and Cu or between Cd and Zn.
