Extractive fermentation was used for phenylalanine production to prevent the crystallization of phenylalanine during the fermentation. Instead of the conventionally used ion exchange resin, uncharged polystyrene beads (Amberlite XAD-16) were used to extract phenylalanine from the fermentation broth. The experimental results obtained using a baffled shake flask showed that phenylalanine was not produced when the beads were added at the same time as the inoculum. From the detailed studies, it was found that hydrophobic nutrients such as tyrosine and colored materials from the soybean hydrolysate adsorbed onto the beads as well as phenylalanine. In order to overcome this problem, the beads were gradually added during the course of the fermentation to minimize the adsorption of the hydrophobic medium components. Using the gradual addition of the polymeric beads during fermentation, an equivalent amount of phenylalanine was produced as compared to the control, and 40% of the phenylalanine produced was extracted during the fermentation. It was concluded that extractive fermentation using polymeric beads could be an effective way of preventing the crystallization of phenylalanine during fermentation.