Disclosed are polymeric dyes obtained by the reaction of (a) a basic polycondensate with (b) an electrophilic dye of formula (2) P—X—Ya+ Ana+; wherein the basic polycondensate (a) is obtained by the reaction of (a1) an amine of formula (I) in the presence of an anhydrous solvent with an ammonium salt (a2) with a cyanamide: Wherein P, X, Y, a+, a, a1, a2, An, R1, R2, R3, R4, R5, R6 and A are defined in the claims and in the disclosure. The present invention also relates to compositions comprising these polymeric dyes, to a process for their use for dyeing of organic materials, such as keratin fibers, wool, leather, silk, cellulose or polyamides.