A rapid and sensitive spectrophotometric method for the determination of diosmin (D) has been developed. The method is based on the reaction of D with 4-aminoantipyrine (AAP) in the presence of hexacyanoferrate (III) (HCF) in an alkaline medium and subsequent formation of a purple coloured product havingmax at 524.5 nm. The conditions affecting the reaction (reagents concentration, pH, order of addition of reagents, stability in time) were optimized. Under the optimum conditions, Beer's law was obeyed in the range of 0.3 - 35 μg mL -1 D with a correlation coefficient of 0.9993. The assay limits of detection and quantitation were 0.1 and 0.3 μg mL -1 , respectively. The proposed method was successfully applied to the analysis of the drug tablets formulation. The results were compared favorably with those obtained by other reported methods.