A theory is outlined for analyzing the observed mean Doppler shift of Fraunhofer lines in the zodiacal light, assuming that the particle distribution in terms of composition, size, and shape is constant throughout the interplanetary medium. The theory is applied to the observed Doppler shift of H-beta; the Doppler shift in and out of the ecliptic plane for elliptical and circular orbits of the zodiacal dust is calculated for several different density distribution functions. Mean Doppler shifts and lines of equal Doppler shift on the sky are plotted as a function of or for various values of different parameters. It is found that the curves of the lines of equal Doppler shift for the same distributions are symmetrical in the ecliptic plane and antisymmetrical in the plane of the solar meridian, that the Doppler shift along the solar meridian is zero for all distributions, and that the Doppler shift is particularly sensitive to changes in the distribution of eccentricity assumed for the dust.