Lactose (C₁₂H₂₂O₁₁ FW: 342.3) is an important naturally occurred disaccharide, consisting of one galactose and one glucose. Milk contains ~2-8% lactose. Some people, particularly infants, lack the enzyme necessary to digest galactose leading to galactose accumulation in blood (Galactosemia) causing enlarged liver, renal failure, cataracts and brain damage. In the BioVision Lactose Assay Kit, Lactose is hydrolyzed to glucose and galactose. The galactose is subsequently oxidized generating color (O.D 570 nm) and fluorescence (Ex/Em 535/587 nm). Free galactose can be corrected by a background control in the absence of lactase. The Lactose Assay Kit provides a simple, convenient, and sensitive means for direct measurement of lactose levels in various biological samples (serum, plasma, other body fluids, food, growth media, etc.). Pretreatment of samples is not required. The kit can be used as a high throughput assay.