Abstract: Mixtures of at least two water-insoluble monoazo dyestuffs of the formula: ##STR1## wherein D is the residue of a diazo component of the benzene series free from sulphonic acid and carboxyl groups which may be substituted with one or more optionally substituted alkyl, alkoxy, alkoxyalkyl, acyloxy, alkylcarbonyl and/or alkoxycarbonyl groups and/or one halogen atom, R is hydrogen, halogen or an optionally substituted alkoxy group and A is an aromatic radical which may be substituted with one or two optionally substituted alkyl and/or alkoxy groups and/or one halogen atom, can be used for the coloration of textile materials consisting at least partly of linear, aromatic polyesters. The melting points of these mixtures are lower than those of their individual dyestuff components, preferably lower than 200.degree. or 180.degree. C.