Aspergillus tamariiwas able to produce biomass in media containing β-methylD-xyloside, a synthetic analogue of xylobiose, as the only carbon source. β-MethylD-xyloside was a more effective inducer than xylan at the same concentration for xylanase and β-xylosidase activities. The delayed consumption of β-methylD-xyloside byA.tamariicells suggests the requirement of a specific inducible transport system and a slow metabolic process. The synthesis of this transport system was probably repressed by the presence of easily metabolizable sugars. β-MethylD-xyloside was hydrolyzed to xylose by an intracellular β-xylosidase.Key words: xyanolytic microorganisms, xylanase, β-xylosidase,Aspergillus tamarii.