PURPOSE: A fiber is provided to be obtained by copolymerization of a compound containing an acidic end group and having a basic nature while having the amino end group content for less than 10 meq/kg. CONSTITUTION: The invention relates to an acid-dyeable polyamide fibre which can be obtained very reproducibly and unsusceptibly to faults during the production process. The fibre is characterized in that the amino end group content is less than 10 meq/kg. A very reproducible affinity for dyestuff is obtained by copolymerization of a compound containing an acidic end group and having a basic nature. Compounds derived from melamine are particularly suitable.
