ESDU Aero W.S.02.03.09 presents a graph, using parameters defined by transonic similarity laws, of the variation of the wave drag coefficient at zero lift as a function of Mach number, aspect ratio and thickness/chord ratio for wings with symmetrical NACA 65 series sections. The data were experimentally obtained from rocket propelled models or models in free fall and drag was obtained from a balance or by the difference between the drag of the wing-body combination and the body alone based on deceleration measurements. The span to body diameter ratio was in the range 3.8 to 5.7 and Reynolds number, based on wing chord, was between 2 and 8 million. Some two-dimensional data are included from wind-tunnel tests. It is recommended the data be used for qualitative guidance only as the scatter is up to 25 per cent probably due to the unknown effects of surface finish, transition position and Reynolds number.