The invention relates to a process for dyeing keratinous fibres, which consists in applying to these fibres a composition containing, in a suitable medium for dyeing, at least one coupler of formula: ##STR1## where R.sub.1 denotes hydrogen or alkyl,R.sub.2 and R.sub.3 denote hydrogen, alkyl, COOR' where R' is alkyl or hydrogen,at least one of the groups R.sub.2 and R.sub.3 denoting hydrogen,R.sub.4 denotes hydrogen, alkyl, hydroxyalkyl, polyhydroxyalkyl or aminoalkyl,Z.sub.1 and Z.sub.2 denote hydrogen, alkyl, hydroxyl, halogen, alkoxy,at least one of the groups Z.sub.1 and Z.sub.2 is other than hydrogenat least one oxidation dye precursor,at least one oxidizing agent, the pH of the composition applied to the fibres being higher than 7.