A method has been devised for the simultaneous determination of a- and [3-carotene in mixtures. All measurements are done spectrophotometrically in the range of 420 nm to 480 nm. A new constant, the V-value, is introduced for characterisation of the absorption spectrum and to follow the degradation of a- and (3-carotene in solution. The quantitative determination of a- and (3-carotene in mixtures containing approximately 0.03 to 0.2 mg % total carotene (a + (3) in differing ratios gave good and reproducible results (standard deviation 0.007 mg %).