In this paper, a new dual boundary element formulation is presented for dynamic crack problems in Mindlin plates. The displacement and traction boundary integral equations are derived in the Laplace frequency domain to allow for a boundary-only formulation. The cracked plate is modelled with the dual boundary element method and dynamic plate bending stress intensity factors are evaluated. Four benchmark examples are presented including mode I and mixed mode deformation. Such stress intensity factors obtained are shown to be in excellent agreement with finite element results as well as published results.