In this paper dual boundary element method for analysis of cracked stiffened panels under dynamic loading is presented for the first time. A continuously attached stiffener is considered. The time-dependent solutions are obtained by the Laplace transformed method. The stress intensity factors are presented for an inclined central crack in a plate with two symmetrically placed stiffeners either side of the crack. The dynamic stress intensity factors are found to be around 2.5 times higher than their respective static values. The stiffeners are shown to be effective in reducing the stress intensity factors.