The performasnce of a recycle two-stage fermentor with cell separators after each stage is analyzed numerically for continuous production of lactic acid. In this system, the bleed broth withdrawn from the first stage is provided to the second fermenter to reuse viable cells in the bleed. Biological rate expressions and parametric values are taken from the literature, The effects of operating parameters on the concentrations of total and viable cells, substrate and product in each stage, the lactic acid productivity and the substrate conversion are examined and discussed. With respect to overall productivity and conversion, it is found that the present fermenter system is more efficient than a conventional chemostat fermenter with cell recycle.