Cs removal from radioactive wastewater by poly-γ-glutamic acid was studied. High adsorption capacity of poly-γ-glutamic acid for Cs removal was obtained. Langmuir model could successfully represent the isotherm data of Cs removal. The adsorption of Cs by γ-PGA attained the equilibrium very quickly. Potential utilization of poly-γ-glutamic acid for Cs removal was confirmed.