More than 40 FPL yeast strains of P.stipitisand C. More than 40 FPL yeast strains of P. stipitis shehatae were screened to determine their fermentation rates on mixed sugars. All of the tested FPL strains fermented both glucose and xylose. The average ethanol concentration attained was 34:8 _ 2:42 g/l with P. stipitis and 34:0 _ 1:67 g/l with C. shehatae. The average ethanol yield was 0:44 _ 0:02 and 0:43 _ 0:02 g/g for P. stipitis and C. shehatae, respectively. Some C. shehatae strains exhibited 50±60% less cell growth than did P. stipitis strains for the same amount of sugar consumed. Consequently, C. shehatae had higher speci fic ethanol production rates. Strains of C. shehatae generally assimilated glucose and xylose faster than did P. stipitis strains. Production of polyols was lower than that of other sugars in both yeast strains under these fermentation conditions.