5,2′,5′-Trihydroxy-3,7,4′-trimethoxyflavone-2′- O-glucoside, a major flavonoid constituent of Chrysosplenium americanum Schwein. ex Hooker was conjugated to bovine serum albumin (BSA) by the diazo reaction in good yield and with a molar ratio of 11.5:1. Antibody raised against the latter conjugate had a titer value of 1:1600 and was found to be specific for the 2′- O-glucosides of tri- and tetramethoxyflavones. Some cross reactivity (about 55%) was observed against the pentamethoxyflavone-5′- O-glucoside; but almost none with the parent hydroxyflavone, quercetin, or any of its partially methylated (3,7,4′-tri- or 3,7,3′,4′-tetramethyl-) derivatives. The specificity of antibodies raised against the 2′- O-glucosides of Chrysosplenium makes them useful for the intracellular localization of these natural constituents.