Under oxygen transfer rates (OTR), from 10 to 30 mmol . l(-1)h(-1), Candida boidinii NRRL Y-17213 exhibited both NADH and NADPH linked D-xylose reductase activities with the former being higher. Xylitol dehydrogenase was mainly NAD dependent. Maximum xylitol production was attained at OTR of 14 mmol l(-1)h(-1). Ethanol, glycerol and ribitol were also produced. A correlation between xylitol accumulation, oxygen availability and key enzyme activities was viewed.