Furfural (300 mg/L) reduced xylose conversion to xylitol in the absence of glucose. The suppressory effect of furfural was reversed by adding glucose (3 g/L). With added glucose and furfural, xylitol productivity exceeded 1.0 g/L h. Glucose and furfural together enhanced xylitol production relative to control. A final xylitol concentration of nearly 28 g/L was obtained with furfural present.