Abstract: The invention is related to a process for the production of improved, low shrinkage, highly oriented polyester threads which comprises melt spinning a polyester thread, stretching said thread in hot water and shrinking said thread from 3 to 22 % in hot air at temperatures of from 5.degree. to 40.degree. C below the melting point of the polyester over a period of from 3 to 30 seconds. The improved service properties of monofilaments produced in this way are reflected in an increase in the ultimate tensile strength coupled with an increase in elongation, in a shrinkage of less than 1% on boiling, in a heat-included shrinkage of at most 10% at a temperature of 195.degree. C (exposed for 30 minutes in air) and in a very high 2nd moment.