Continuous production of L-ornithine by an arginine auxotroph of Brevibacterium ketoglutamicum was carried out in a 2-l jar fermenter. The effects of the dilution rate on the fermentation parameters were investigated under L-arginine limited conditions. The maximum L-ornithine yield and volumetric productivity obtained were 0.213 g/g and 0.313 g/l/h, respectively. The specific L-ornithine production rate increased with the dilution rate, with a maximum value of 0.084 g/g/h at a dilution tate of 0.125 h(-1).