In order to characterize chemically bonded phases in high performance liquid chromatomatography analysis, the retention behaviors of fifteen steroids including estrogen, androgen, progestogen and corticoid were systematically examined by using ethyl acetate as a stronger component in an n-hexane-binary system. A linear relationship between the logarithm of the capacity ratio and that of the molar concentration of the binary solvent was confirmed for aminoand cyano-type bonded silica gel columns. On the basis of the retention indices of the bonded and non-bonded silica phases, the retentivity of the packing materials was determined as follows : amino-type is slightly stronger (1.1 times) and cyano-type weaker (0.6 times) than bare silica gel. The specific retentivity of an amino-column for polar steroids containing phenolic and alcoholic hydroxyl groups suggests a molecular interaction associated with hydrogen bonding between the polar packing surface and solute compounds. The selectivity of amino packing was found to be larger than cyano packing whose retention selectivity is similar to a bare silica gel.