Abstract: Polyethylene Terephthalate fiber having a relative viscosity of 1.50 to 1.70 is drawn in two stages. In the first stage the fiber is drawn at a draw ratio of from about 3.8 to 4.2 at a temperature of about 70.degree.C to about 100.degree.C. In the second stage the fiber is drawn in superheated steam at a temperature of about 210.degree.C to 250.degree.C at a draw ratio such that the total draw ratio for the two stages is from about 5.6 to 6.0. The fiber produced has a tenacity of at least about 7.5 grams per denier, an elongation at break of at least about 9%, an elongation of not more than about 5% under a load of 5 grams per denier and a shrinkage of less than 4% when kept under a tension of 0.05 grams per denier for 4 minutes at about 160.degree.C. The fiber is especially suitable for reinforcing bitumen-containing materials.