The antipsoriatic drug anthralin (dithranol) is known to be extensively accumulated inside mitochondria of keratinocytes and to interact with the electron flow of the respiratory chain. Primary products of the one-electron reduction of polyphenolic anthralin observed in vivo are its dehydrogenated anions, which are formed by H-atom abstraction. The same species are mainly generated at low electron energies by dissociative electron attachment (DEA) to anthralin molecules in vacuo. A likely mechanism for the biochemical transformations of anthralin under reductive conditions in vivo is hypothesized on the basis of its DEA properties. The involvement of excited electronic states generated by ultraviolet irradiation of skin is discussed.