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.