Abstract: The correlation relationships among amino acid residues in protein structures are studied. Some residue pairs have larger correlation coefficients and they are not independent of protein structural classes. The correlation relationships of amino acid residues are the earmarks of protein structural classes and have special physical and chemical causes. These correlation relationships are used in the predictions of protein structures for α,β,α/β, and α＋β protein classes, in total 204 proteins. The prediction accuracy are 94％ (α-proteins),89％ (β-proteins),79％ ((α/β)-proteins) and 89％ ((α＋β)-proteins),higher than the results of the simple distance method and the Euclidean distance method.

Key words: Correlation of amino acids, Prediction of protein structure, 　Bioinformatics