Low speed wind tunnel measurements have been made on a 1.15m span 60º delta wing with rounded leading-edge vortex flaps. the purpose of the measurements was to assess the benefits of the measurements was to assess the benefits of the rounded leading-edge vortex flaps on the lift/drag ratio. The force and surface pressure measurements were made at a Reynolds number based on the centreline chord of 2x106. The increase in the radius of the rounded leading-edge reduces the drag significantly both with and without flap deflection except in the minimum drag region. Deflecting the rounded leading-edge vortex flap improves the lift/drag ratio compared with the sharp edged vortex flap at relatively higher lift coefficients. The greatest percentage improvement in the lift/drag ratio compared with the sharp edged flat delta wing is more than 50% at a lift coefficient of 0.5 for the rounded edge delta wing with flap deflected.The University