A dye composition for keratinous fibres comprising a solvent and at least one dye which is a compound of formula: ##STR1## in which R.sub.1 and R.sub.2 are each, independently of each other, hydrogen, an alkyl group, a mono- or polyhydroxylated alkyl group, an alkyl group substituted by an alkoxy or hydroxyalkoxy group, or an aminoalkyl group, the amino group of which is optionally substituted with one or two alkyl or hydroxyalkyl groups, and it being possible for the nitrogen atom also to form part of a heterocyclic ring, all the abovementioned alkyl groups or moieties containing from 1 to 6 carbon atoms, or, of the compound of formula (I) contains an amino group which can be salified, a cosmetically acceptable salt thereof.