In this study, poly(ethylene glycol dimethacrylate-N-methacryloyl-l-tryptophan methyl ester) [poly(EGDMA-MATrp)] beads (average diameter = 106-300 mu m), which were synthesized by co-polymerizing of N-methacryloyl-l-tryptophan methyl ester (MATrp) with ethylene glycol dimethacrylate (EGDMA), were used for diethyl phthalate (DEP) adsorption. The various factors affecting the adsorption of DEP from aqueous solutions such as pH, initial concentration, contact time and temperature were analysed. Adsorption behaviour of DEP on the poly(EGDMA-MATrp) beads was investigated by varying pH values of solution, contact time, initial concentration and temperature. An optimum adsorption capacity of 590.7 mg/g for DEP was obtained at 25 degrees C. The present adsorption process obeyed a pseudo-second-order kinetic model. All the isotherm data can be fitted with the Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. Thermodynamic parameters Delta H = 7.745 kJ/mol, Delta S = 81.92 J/K/mol and Delta G = -16.69 kJ/mol to -18.31 kJ/mol with the rise in temperature from 25 degrees C to 45 degrees C indicated that the adsorption process was endothermic and spontaneous.