The invention comprises naphthoquinone imines (I) having the formula <FORM:1097271/C4-C5/1> and tautomers thereof, wherein n is 1-3, which are obtained by condensing 5,8-dihydroxy-1,4-naphtho quinone with the appropriate alkylene polyamine and (2) having the formula <FORM:1097271/C4-C5/2> and tautomers thereof wherein R represents a hydroxyalkyl aminoalkyl radical or a phenyl radical bearing an amino group -NR1R2 wherein either R1 is alkyl and R2 is hydrogen or alkyl or R1 and R2 are hydrogen or monoor poly-hydroxyalkyl, at most one of R1 and R2 being hydrogen, the formula <FORM:1097271/C4-C5/3> and tautomers thereof wherein R1 is -alkylene-or -(alkylene-NH)n-alkylene-, n being 1 to 3, or the formula <FORM:1097271/C4-C5/4> and tautomers thereof, wherein X is a monovalent radical R or a divalent radical -R1-or -R1-R1-, r being 1 or 2 according to the valency of X and R and R1 are the heterocyclic groups; 2-pyridyl, 3-pyridyl, 6-amino-2-pyridyl, 2 - methyl - 4 - thiazodyl, 4 - quinolyl, 7-quinolyl, 2 - imidazolyl, 5 - benzimidazolyl, 2-benthiazolyl or 2-naphtho-(1,2)-thiazolyl.  The imines of (2) and other analogous naphthoquinone imines are prepared by condensing a primary mono- or di-amine with 5-amino-8-hydroxy - 1,4 - naphthoquinone - 1 - imine (NI); condensation of the di-amine with two moles of NI yield a bis-naphthoquinone imine. Numerous examples are given of the condensation of NI with primary alkyl amines, N-hydroxyethyl ethylene diamine, polyhydroxy alkyl amines, alkylene polyamines, hydroxy and alkoxy aromatic amines, hydroxy alkyl phenylene diamines, dialkylamino aromatic amines, nitro anilines, amino benzyl alcohols, and heterocyclic amines.  NI is prepared by reacting 1,5-dinitro naphthalene with sulphuric acid and purified by heating it in an aqueous solution of a secondary or tertiary alkanolamine followed by precipitation with brine. The NI may be sulphonated by adding the imine in powder form to oleum at 25-30 DEG  C. The various imines and others of the general formula <FORM:1097271/C4-C5/5> and tautomers thereof wherein X is a monovalent radical -R or a divalent radical -R1-, wherein R is hydrogen or a monovalent aliphatic, cycloaliphatic, aryl, aralkyl or heterocyclic radical and R1 is a divalent aliphatic, cycloaliphatic, arylene, aralkyl or heterocyclic radical, r is 1 or 2 depending on X and A, B, C, D, E and G are hydrogen, chlorine, bromine, sulpho, alkyl or -HNR, where R is as defined above and wherein A and B may also be hydroxy, may be used for hair dyeing (see Division D1).ALSO:Human hair is dyed on the head with a substantive naphthoquinone imine represented by the formula <FORM:1097271/D1-D2/1> wherein X is a monovalent radical -R or divalent radical -R\svwherein R is hydrogen or a monovalent aliphatic, cycloaliphatic, aryl, aralkyl or heterocyclic radical and R\sv is a divalent aliphatic, cycloaliphatic, arylene, aralkyl or heterocyclic radical, r is 1 or 2 depending on the value of X and A, B, C, D, E and G are hydrogen, chlorine, bromine, sulpho, alkyl or -HNR where R is as above defined and wherein A and B may also be hydroxy.  The dyes may be used in aqueous media which are acid or alkaline, alone or with other direct dyes and/or with oxidation dyes, including nitro, azo, phenolic and anthraquinone dyes and phenylene diamines.  The oxidation dyes are used in conjunction with H2O2 or urea peroxide.  The dyes may be used together with conventional anionic, cationic or non-ionic surfactants and with thickening agents.  Numerous examples are given.