A study was conducted to establish the toxicity evaluation of xylanases from Penicillium occitanis Pol6 and the expressed ones in the methylotrophic yeast Pichia pastoris to be used as a processing aid in the baking industry. The dose delivered in the acute study was therefore 2000 mg/kg body weight samples powder. The subchronic study of these xylanases was performed inWistar rats at a dose level of 12000 UTX/kg body weight/day (this dose is three times the maximum dose of xylanase to be expected in bakery products). Body weight, food and fluid intake, antioxidant enzyme activities, biochemical parameters in plasma and urine and hematological parameters were obtained. Histopathology by light microscopy was performed. Furthermore, the expressed xylanase preparation was found not to represent mutagenic or clastogenic potential in the bacterial reverse mutation assay. According to the results of this study, the studied xylanases possess no discernible risk to human health and no adverse effects were detected by oral administration.