Production feedback inhibition both on cell growth and on product formation of phenylalanine fermentation might be alleviated by elevated oxygen supply. Batch fermentations by a high phenylalanine producing strain Corynebacterium glutamicum CCRC 18335 at various initial phenylalanine concentrations (PO) ranging from 0 to 20 g/L and different oxygen transfer rate coefficients (K(L)a) ranging from 23 to 76 h(-1) were studied. The fermentation parameters with respect to P-0 were strongly dependent on K(L)a. Cell yield favored higher K(L)a and lower P-0. Product yield with respect to varying phenylalanine concentration was evaluated by the relative oxygen availability (ROA). The optimal ROA for phenylalanine formation was strongly dependent on the product concentration. While P-0 was low, the product inhibition was less significant and the maximum product yield occurred while ROA was at 0.5-0.6. While P-0 was high, the product inhibition was significant and the maximum product yield occurred while ROA was at 0.8-0.9. These results suggest that the product feedback inhibition of phenylalanine fermentation processes can be alleviated by a gradual increase in oxygen supply rate while the increasing product concentration is taken into account. The strategy is demonstrated in a fed-batch culture with elevated oxygen supply. The final phenylalanine concentration was 23.2 g/L, which was 45% better than that of the fed-batch fermentation without elevated oxygen supply. Likewise, the maximum productivity was improved by 42% at 0.37 g/(L (.) h).