This European Standard specifies a method for the determination of melamine and cyanuric acid in foodstuffs with liquid chromatography in combination with tandem mass spectrometry. The method has been validated in an interlaboratory study via the analysis of spiked samples of milk based infant formula, soy based infant formula, milk powder, whole milk, soy milk and milk chocolate ranging from 0,71 mg/kg to 1,43 mg/kg for melamine and 0,57 mg/kg to 1,45 mg/kg for cyanuric acid. The limits of quantification (LOQ) for melamine and cyanuric acid in food are 0,05 mg/kg and 0,25 mg/kg, respectively. The upper limit of the working range is up to 10 mg/kg for melamine and up to 25 mg/kg for cyanuric acid.