The free cells of Candida krusei were recycled during repeated batch fermentation to produce glycerol. The kinetics of glycerol formation with recycled cells washed and not washed was studied. Some inhibition was found during cell recycling but could be removed by washing recycled cells. In 12 cycles of repeated batch fermentation with recycled washed cells, glycerol productivity increased greatly during the earlier three cycles and then remained constant in the following cycles. Kinetic studies showed that higher glycerol productivity in repeated batch fermentation compared with that in ordinary batch fermentation was due to the high biomass concentration. (C) 2003 Elsevier Ltd. All rights reserved.