Polyazo dyestuffs capable of being after-coppered on the fibre and having the general formula <FORM:0601266/IV (c)/1> (in which R1, R2 and R3 represent unsulphonated benzene nuclei, of which R1 contains an oxy-group in ortho-position to the azo group, R2 contains the -NH- and azo groups in 1,4-position relatively to one another, and R3 contains a hydroxyl group in 4-position to the azo group and a carboxyl group in orthoposition to the said hydroxyl group, and R4 represents an unsulphonated benzene nucleus which may, if desired, contain as a substituent in the 4-position relatively to the -NH- group a -N=N-R5 group, in which R5 represents a benzene nucleus free from sulphonic acid groups and containing a hydroxyl group in 4-position relatively to the azo-group and a carboxyl group in ortho-position to the said hydroxyl group) are prepared from 1 mol. of a diazotized ortho-aminophenol free from sulphonic acid groups, 1 mol. of 2-amino-5-oxynaphthalene-7-sulphonic acid, 1 mol. of cyanuric chloride or bromide, and 1 or 2 mols. of a 4-amino-41-oxy-1,11-azobenzene-31-carboxylic acid or 1 mol. each of two such acids, the order of succession of the operations and the conditions being such that the diazo-compound couples in the 6-position of the amino-oxynaphthalene sulphonic acid, one halogen atom of the cyanuric halide reacts with the amino group of the amino-oxynaphthalene sulphonic acid, 1 or 2 halogen atoms of the cyanuric halide react with the amino group or groups of the amino-oxy-azobenzene carboxylic acid or acids and, if an unreacted halogen atom remains, this is reacted with a primary amine of the benzene series free from sulphonic acid groups. In a modified process, the amino-oxy-azobenzene carboxylic acid or acids are replaced by an amine or amines of the benzene series containing an amino group or a group convertible thereto in the 4-position, and the product is diazotized or tetrazotized and coupled with 1 or 2 mols. of an ortho-oxy-benzene carboxylic acid or acids capable of coupling in paraposition to the hydroxyl group, these reactions being carried out after reaction of the cyanuric halide with the 2-amino-5-oxynaphthalene-7-sulphonic acid and the coupling with the diazotized ortho-aminophenol. In a modification, and by similar procedures, dyestuffs of the general formula <FORM:0601266/IV (c)/2> are obtained from 1 mol. of a diazotized orthoaminophenol free from sulphonic acid groups, 1 mol. of 2-amino-5-oxynaphthalene-7-sulphonic acid, 1 mol. of phosgene and 1 mol. of a 4-amino-41-oxy-1,11-azobenzene-31-carboxylic acid. In examples: (1) 1-amino-2-oxybenzene-5-sulphonamide (1-amino-2-oxy-5-nitrobenzene or 1-amino-2-oxy-5-chlorobenzene) is diazotized and coupled in alkaline solution with a condensation product obtained from 1 mol. each of cyanuric chloride, 2-amino-5-oxynaphthalene-7-sulphonic acid, 4 - amino - 41 - oxy - 1,11 - azobenzene-31-carboxylic acid and aniline; (2) 1 - amino - 2 - oxybenzene - 5 - sulphonamide - (1 - amino-2-oxy-5-nitrobenzene or 1-amino-2-oxy-5-chlorobenzene) is diazotized and coupled in alkaline solution with the condensation product obtained from 1 mol. of cyanuric chloride, 1 mol. of 2-amino-5-oxynaphthalene-7-sulphonic acid and 2 mols. of 4-amino-41-oxy-1,11-azobenzene-31-carboxylic acid; and (3) cotton is dyed in a bath containing the dyestuff of example (1) under addition of sodium sulphate and the dyebath is then neutralized and copper sulphate and tartaric acid added. Specifications 209,723, [Class 15 (ii)], 221,843 and 315,665, [both in Class 2 (iii)], are referred to.