The present invention relates to a novel method for quantifying procyanidin and flavan-3-ols contained in natural products, foods and drinks, pharmaceuticals and/or cosmetics. The present invention provides a method for quantifying procyanidin (a generic name for a mixture of catechin n-mer; n ‰§ 1) contained in test samples such as natural products, foods and drinks, pharmaceuticals and/or cosmetics, which comprises a) pretreating a test sample using a column to remove contaminants which affect the analysis of procyanidin and flavan-3-ol; and b) effecting high performance liquid chromatography (HPLC) to separate and quantify procyanidin and flavan-3-ols in the solution treated to remove contaminants during the above pretreatment step a).