Abstract—–Products of oxidation of β‐carotene, photosensitized by hypericin in acetone, appear to include mutatochrome, aurochrome, and a number of other compounds absorbing in the violet and near u.v. regions of the spectrum. The 5, 6‐monoepoxide is not formed in appreciable quantity, though it is the principal product of oxidation of carotene by perphthalate. Mutatochrome, lutein, and zeaxanthin are photooxidized more slowly than β‐carotene, and the products do not appear to include 5, 6‐epoxides. β‐carotene‐5, 6‐monoepoxide is oxidized to what is probably luteochrome. Quantum yields appear to be low. We found no evidence to support a photochemical contribution to the oxidation of zeaxanthin to violaxanthin, a process known to acco