The kinetics of asymmetric production of R-(-)-mandelic acid (R-MA) from phenylglyoxylic acid (PGA) catalyzed by Saccharomyces cerevisiae sp. strain FD11b was studied by fed-batch cultures. The concentrations of glucose and PGA were controlled respectively with a dual feeding system. When the electron donor glucose was supplied at the rate of 0.0833mmol.gdw(-1).h(-1), the specific production rate (q(p)) and the enantiomeric excess of R-MA reached the maximum 0.353 mmol.gdw(-1).h(-1) and 97.1%, respectively. The apparent reduction activity of yeast FD11b was obviously affected by both substrate PGA and product MA. The qp value reached the maximum 0.36-0.38mmol.gdw(-1).h(-1) when the PGA concentration was controlled between 25 and 35mmol.L-1. The obvious substrate inhibition of bioconversion was observed at the PGA concentrations higher than 40mmol.L-1. The accumulation of product MA also caused a severe feed-back inhibition for its production when the product concentration was above 60mmol.L-1. The kinetic model with the inhibition effect of both substrate and product was simulated by a computer-based least-square arithmatic. The established kinetic model was in good agreement with the experimental data.