Process for continuously dyeing filaments of slivers of wet-spun acrylonitrile polymers

A process for the continuous, uniform and penetrative dyeing with high fastnesses of a sliver or a filament of an acrylonitrile copolymer which has been produced by a standard wet-spinning process, which comprises subjecting the unstretched filament or sliver before dyeing to a combined washing, pressing and drying pretreatment by washing said filament or sliver once or several times at a temperature of up to 70.degree. C, squeezing it out between squeezing rollers and drying it under the effect of heat, so that the spun material has a residual moisture content of at most 10% by weight and a residual solvent content of at most 4% by weight of the residual moisture content, and thereafter dyeing said filament or sliver in a dye bath over a period of from up to 60 seconds at a temperature in the range of from 20.degree. to 100.degree. C, stretching to between 2.5 and 6.5 times their original length and aftertreating.