The invention relates to a process for the preparation of nitroanilines, which consists in reacting an amine RNH.sub.2, or ammonia, with 3,4-methylenedioxynitrobenzene to give the products of the formula: ##STR1## in which R denotes hydrogen, alkyl, monohydroxyalkyl or polyhydroxyalkyl, alkoxyalkyl or aminoalkyl of the formula: ##STR2## in which R.sub.1 and R.sub.2, which are identical or different, denote hydrogen, alkyl or monohydroxyalkyl or polyhydroxyalkyl and n denotes an integer from 2 to 4, or of the formula: ##STR3## in which A denotes OCH.sub.2 or ##STR4## and R.sub.1 denotes --CH.sub.2 CH.sub.2 OH or ##STR5## or their salts. The invention also relates to the dyeing compositions for keratin fibres, and in particular for hair, which contain a dyestuff of the above formula (I) in which R denotes alkyl, polyhydroxyalkyl, alkoxyalkyl or aminoalkyl of the abovementioned formula, and to the dyestuffs of the formula (I) in which R denotes alkoxyalkyl or aminoalkyl of the above formula, and of the formula (IIB), which are novel.