The question of the effect of wall vibrations on the tone of an organ flue pipe is examined theoretically and experimentally. The effect of nonrigid walls is calculated and it is shown that, if they do not affect the pipe frequency, they do not radiate appreciably. For pipes as ordinarily constructed of circular or nearly circular cross section, the lack of rigidity of the walls will have negligible effect. The wall vibrations actually occurring in sounding organ pipes were investigated experimentally and found to be owing to the vibrating air stream from the flue impinging on the lip. By artificially vibrating pipes to the same acceleration levels as when blown, it was found that the sound radiated from the vibrating walls is negligible. By surrounding pipes with a jacket and filling the space between with water, it was determined that the wall vibrations do not affect the internal standing wave in the pipe. Measurements of pipes in other organs confirmed the laboratory findings. It is concluded that the steady tones of organ pipes are not affected by wall vibrations.