Abstract: The invention provides a dye composition for dyeing fibers comprising (a) an azo dye of formula (II) or a salt thereof, and (b) an azo dye of formula (III) or a salt thereof. The invention provides navy and black dye compositions, especially suitable for dyeing secondary cellulose acetate fibers, with superior fastness properties than known navy/black dyes. Preferably, the &agr;-crystal form of dye (III) is used, which has greater solubility and achieves quicker dyeing than the commonly-used &bgr; and &ggr; forms of (III) when dyeing cellulose acetate at 60-95° C. A new method of making the &agr; form is disclosed.