The production of the amino acid L-phenylalanine (Phe) by fermentation is in many cases limited by the tight regulation of the microbial pathway leading to Phe synthesis. One way of circumventing feedback repression is to remove the product from the vicinity of the micro-organism as soon as it is being formed. In the case of Phe, techniques like adsorption and extraction have been applied with this aim. In these processes, however, additional recovery steps are required in order to obtain the product as anhydrate crystals, which is its commercial form. In this work we evaluated conceptually the recovery of Phe anhydrate crystals during a fermentation process. The product recovery consisted of water removal by reverse osmosis, crystallization, and recycle of the mother liquor either to the fermenter, to the water removal unit or to both. By maintaining the Phe mass fraction in the fermenter at about 17 g kg(-1) the Fermentation productivity increased according to the calculations from 0.66 g kg(-1) h(-1), Without product removal, to 1.07 g kg(-1) h(-1), with product removal, where about 70% of the produced Phe was directly recovered as anhydrate crystals. By means of a simplified economic model it was shown that the membranes required for cell retention and water removal have much more impact oil the economic performance of the process than the consumption of raw materials, and therefore, the favored recycling option for the mother liquor is to the water removal unit.