Shock tube experiments have been conducted to determine the effect of surface roughness on shock waves in nitrogen passing over the surface. Shock retardation was measured for a series of two‐ and three‐dimensionally rough surfaces at shock strengths from ξ=0.1 to ξ=0.9. The first‐order approximation was made that the volume between the positions of the shock wave, with and without the rough surface present, multiplied by the specific energy behind the undisturbed shock wave represented energy dissipated by the roughness. The space rate of energy dissipation is presented as a function of the average particle size of the rough surface. It is also shown that the curvature of the shock wave in the vicinity of the surface depends on the roughness of the surface, the length of roughness covered, and the strength of the shock wave. In addition, the hundreds of measurements of shock wave contours made in this investigation showed that there is a random fluctuation in the angle of incidence of the primary shock wave of 1/15°. This fluctuation is presumably caused by the details of the diaphragm rupture even though measurements were made 14 ft from the diaphragm in a shock tube with a 2×7 in. cross section.