Elastodynamic stress-intensity factors accompanying the three-dimensional steady-state elastodynamic response of an unbounded solid containing a semi-infinite crack, are investigated in this paper. Analytic solutions are obtained by application of the Fourier transform technique in conjunction with the Wiener-Hopf method. Two specific examples are worked out. For the diffraction of a plane longitudinal wave, which is incident under an arbitrary angle with the edge of the crack, explicit expressions are presented for the Modes I, II, and III stress-intensity factors. The variation of these quantities with the direction of the incident wave was worked out in detail, and the results are displayed in several figures. The second example deals with the elastodynamic field generated by the application of normal point loads of equal magnitude but opposite sense to the surfaces of the crack. For this case relatively simple approximate expressions are derived for the Mode I stress-intensity factor.