Sialic acid is a general name for nine carbon acidic sugars with N- or O-substituted derivatives. The most common member of these sugars is N-acetylneuraminic acid (NANA). Sialic acid is widely distributed throughout mammalian tissues and fluids including serum. Sialylated oligosaccharides have been shown to exhibit antiviral properties and are also known to influence blood coagulation and cholesterol levels. The Sialic acid level in body fluids is also an important marker for diagnosing cancer. Simple, direct and automation-ready procedures for measuring sialic acid concentrations find wide applications in research and drug discovery. This sialic acid assay uses a single Working Reagent that combines NANA aldolase, pyruvate oxidase and hydrogen peroxide determination in one step. The color intensity of the reaction product at 570nm or fluorescence intensity at lambda ex/em = 530/585nm is directly proportional to sialic acid concentration in the sample.