PET glycolyzates, (A) 620, 72degreesC and (B) 584 mg KOH/g, m.p. 86degreesC, prepared in ethylene glycol containing (A) n-Pr amine, and (B) glycerol, were used, 0-20 wt.%, to modify Polish epoxy resin Epidian 5, epoxy no. 0.49 val/100g, viscosity 30 Pa.s. With 15 or 20% of modifier A or B, Charpy's (unnotched) impact strength rose twice, deflection temperatures fell to 80-90%, bending strength to 50% and Brinell hardness to 30-45% of the nonmodified Epidian 5 value. Tensile strength of glass-reinforced laminates based on the modified resins was higher by 10-35%.