This paper describes the optimization of the recovery of phenylalanine from an industrial waste stream by electrodialysis. An electrodialysis apparatus, consisting of three compartments equipped with ADP and CDS ion exchange membranes, was tested. These membranes without pretreatment appeared to be less efficient than the first pretreatment membranes which were immersed in a salt waste stream for 18 h. The electrodialysis process with pretreated membranes yielded 87% of recovered phenylalanine. Furthermore, this process has also been successful in removing 98% of salts (Na2SO4 and (NH4)(2)SO4), from the initial solution with an average current efficiency in the range of 96%. In the second pretreatment, the membranes were soaked in a bovine serum albumin solution for 2 h before the commencement of the experiment. The results obtained show that the phenylalanine loss is significantly reduced. This loss did not exceed 5% and had an average current efficiency of 98%.