The method of caustics with high-speed photography was employed to study the dynamic behavior of a transverse crack in bimaterial plates, with slant interfaces. Both phases of the specimens were fabricated from epoxy-polymers by casting the one phase successively after the other along its oblique boundary.The results have shown that the cracks propagate, in general, under mode-I conditions and that the interface acts as a decelerator for the propagating crack, which, after passing the obstacle of the interface region, accelerates. The observed decelerations and accelerations were always greater in the brittle phases than those of the ductile ones.The influence of the interface region to the crack propagation velocities was found to be more intense, when the crack propagates from a more brittle to a more ductile phase, than in the opposite case.The zone of interaction of the crack with the interface was wide in the case of the inclined interface, increasing with the angle between interface and the loading axis. In this zone the stress intensity factor at first increases, then decreases to a minimum value on the interface and again increases, as the crack enters in the second phase. The crack paths were always slightly curved with a discontinuous tangent at the interface.