In the present experimental study, effects of yaw angle, β on the flow structure at high angles of attack, α with 70° sweep angle, Λ were investigated using the dye visualization technique. In the case of zero yaw angle, β a pair of leading edge vortices take place on both sides of cords axis are more or less symmetrical over the delta wing. These symmetrical vortical flow structures start deteriorating when angle yaw, β is introduced. Onset of vortex breakdown location on the windward side occurs further upstream, on the other hand, the leading edge vortex on the leeward side breaks down further downstream. A perceivable interactions are consisted between structures of vortical flows developed from pair of leading edge vortices after onset of vortex breakdowns. It can be concluded that the magnitude of the leading-edge vortices, onset of vortex breakdowns, and formation of unsteady flow structures generated after vortex breakdowns are substantially affected by yaw angle, β. Angles, θ1 and θ2 between centerline of the delta wing and both central axes of spiral vortices vary as a function of yaw angle, β.