Xylanase production by a newly isolated Aspergillus foetidus MTCC 4898 was studied using submerged fermentation under shaking. The maximum xylanase yield (210 U/ml) was obtained with negligible cellulase activity at 30 °C using 1% birchwood xylan as substrate in 3 days of cultivation. The strain was able to produce extracellular xylanases on birchwood xylan as well as on cellulose rich substrates also with very poor cellulase production (