Chemiluminescence reactions of lucigenin with various biological compounds were examined by a flow injection method. It was found that chemiluminescence from reducing sugars and related compounds was enhanced 100-times when incubated with sodium periodate prior to the reaction with lucigenin. The standard curve of glucose was linear over the range 50pmol-700pmol. Detection limits of glucose with and without treatment of sodium periodate were 50pmol and 50nmol, respectively. Corticosteroids and other compounds having an α-hydroxycarbonyl group in their molecule gave intensive chemiluminescence without treatment of sodium periodate. It was estimated that the α-hydroxycarbonyl group which converts to 1, 2-enediol was essential for the chemiluminescence reaction with lucigenin.