In this paper, the effects of T-stress on steady, dynamic crack growth in an elastic–plastic material are examined using a modified boundary layer formulation. The analyses are carried out under mode I, plane strain conditions by employing a special finite element procedure based on moving crack tip coordinates. The material is assumed to obey the J2 flow theory of plasticity with isotropic power law hardening. The results show that the crack opening profile as well as the opening stress at a finite distance from the tip are strongly affected by the magnitude and sign of the T-stress at any given crack speed. Further, it is found that the fracture toughness predicted by the analyses enhances significantly with negative T-stress for both ductile and cleavage mode of crack growth.