Extractive fermentation using uncharged polymeric beads (Amberlite XAD-16) was used for phenylalanine production. By compensating the adsorption of the hydrophobic nutrients by the polymeric beads, production of phenylalanine was increased due to the removal of phenylalanine inhibition on the growth of the bacteria. When the fed batch culture was performed at low bead concentration, the production of the phenylalanine increased about 30% compared to the control fermentation. An increase of production can be also achieved by using the pre-saturated beads with the hydrophobic nutrients. In addition, the adsorption isotherm in the fermentation medium was investigated. It was found that the adsorption of phenylalanine onto the beads decreased because the adsorption sites can be occupied by nutrients, but this competitive adsorption is not so drastic as to affect the adsorption of phenylalanine during fermentation. This knowledge will be useful when this technology is applied to actual commercial operation.