The simultaneous adsorption of sugar-persubstituted poly(amidoamine) dendrimers (sugar ball) and anionic surfactants such as sodium dodecyl sulfate (SDS) and lithium perfluorooctanesulfonate (LiFOS) on positively charged alumina particles was investigated at pH 3.5 by measuring the amount of adsorbed sugar ball and anionic surfactant, zeta potential, and sedimentation rate of alumina suspensions. The sugar balls of generations G3 and G5 were used. Under constant initial concentrations of the sugar balls, the amount of adsorbed sugar balls sharply increases, reaches a maximum, and then decreases, while the anionic surfactant adsorption increases with increasing anionic surfactant. The enhancement in the adsorption of the sugar balls is due to the adsorption of complexes consisting of sugar ball and anionic surfactant. In addition, the dispersion stability of alumina suspensions caused by the adsorption of the sugar ball and anionic surfactant depends on the zeta potential of alumina as well as the adsorption of sugar ball. A significant difference in the adsorption characteristics is not observed for the generation of sugar ball and kind of anionic surfactant.