AbstractA rapid, simple method for the determination of lactose in milk or milk products is described. An internal standard (galactose) is added to the milk which is then extracted with carbon tetrachloride. A sample of the aqueous layer is injected onto a strongly acidic cation exchange column (Li+form, 17 μm particles) and eluted with aqueous ethanol, the eluent composition being monitored with a modified moving‐wire detector. Applications demonstrating the precision and accuracy of the method are describ