Monoazo dyestuffs are made by coupling a diazo compound of a 3:5-dinitrophenylamine, free from hydroxy groups in the benzene nucleus, with a phenylamine capable of coupling in the 4-position with respect to the amino group. When no groups imparting solubility in water are present the dyestuffs can be used for dying cellulose esters or ethers and tentiles made of superpolyamides or superpolyurethanes and for colouring lacquers, varnishes and artificial masses. When a group imparting solubility is present they may be used for dyeing animal fibres in addition to the above. The diazo compounds of the following are specified:-3:5-dinitro-aniline and 4-methyl-, 2-methyl-, and 4-methoxy- and 4-ethoxy-, 3:5-dinitro-aniline. The following coupling components are specified:-aniline, 2- and 3-methyl-, 2- and 3- methoxy-, 3-acetylamine-and 3-methyl-6-methoxy-aniline, N-dimethyl, N-diethyl-, N-methyl-N-ethyl-, N-oxyethyl-, N-methoxyethyl-N-ethyl-, N-ethoxyethyl-N-ethyl-, M-dioxyethyl-, N-oxyethyl-3-methyl-N-dioxyethyl-3-methyl-, N-ethyl-N-oxyethyl-3-methyl-, N-dioxyethyl-3-methyl-6-methoxy-, N-n-butyl-N-oxyethyl-3-methyl-, <FORM:0584731/IV/1> N-methyl-3-methyl-, N-methyl-N-b :g -dioxypropyl-, N-oxyethyl-N-chloroethyl-, N-di-(acetonyethyl)- and N-n-propyl-N-methoxyethyl-3-methyl-aniline. Other coupling components are those containing, as a group imparting solubility in water, an externally-bound sulphonic acid, sulphuric acid ester or carboxylic acid group, such as the esters with polybasic acids of N-alkylanilines containing a hydroxyl group in the alkyl residue, e.g. N-methyl-N-oxyethyl-3-methyl-aniline sulphuric acid ester and the esters with organic dicarboxylic acids or sulpho-carboxylic acids as described in Specifications 517,918, 545,283 and 565,697, specifically N - oxyethyl - N - CH2.CH2.O.OOC.CH:CH.COOH-, N-methyl-N-CH2.CH2.O.SO3H-2 : 5.-dimethoxy-, N-methyl- or -n-propyl-N-CH2.CH2.O.OC.CHCl.SO3H-, N-oxyethyl-N-CH2.CH2.O.OC.COOH-3-methyl-, N-oxyethyl-N-CH2.CH2.SO3H-, N-ethyl-N-CH2.CH2.O.OC.C6H4.COOH-3-methyl- <FORM:0584731/IV/2> N-CH2CH2.O.OC.CH : CH.COOH-3-methyl-, N-methyl-N-CH2.CH2.COOH-, and N-methyl-N-CH2.CH2.O.SO3H-aniline. Dyestuffs free from these ester groups may be esterified with sulphuric acid or a polycarboxylic or sulphocarboxylic acid or a reactive derivative thereof, e.g. by oxalic acid, maleic acid, maleic anhydride, succinic anhydride, sulphuric acid or sulphochloracetic acid. In the examples the following additional coupling components are specified:-oxalic, maleic and chlorsulphoacetic acid esters of N-methyl-N-oxyethylaniline; chlorsulphoacetic acid ester of dioxyethylaniline. The coupling components may be used in the form of their 2-methane sulphonic acids. In Example 5 cellulose acetate yarn is dyed yellow in a dispersion containing the dyestuff 3:5-dinitroaniline --> aniline, a dispersing agent such as Turkey red oil, sulphite cellulose waste liquor or sulphonation products of the residues from the manufacture of benzaldehyde, soap and water. The chlorosulphoacetic esters of N-methyl-N-oxyethylaniline and N-dioxyethylaminobenzene are obtainable by heating the respective hydroxyethyl compounds with chlorosulphoacetic acid in solvent naphtha. The Specification as open to inspection under Sect. 91 comprises the use, as diazo component, of any 3:5-dinitrophenylamine, and specifies additionally 1-amino-4-chloro-3 : 5-dinitrobenzene. This subject-matter does not appear in the Specification as accepted.