The effect of magnetic fields (MF) on glutathione (GSH) production by Saccharomyces cerevisiae ATCC 7754 was studied. For this purpose, a factorial design of experiments was used to determine the influence of the time of exposure (8-16 h) and MF induction (25.0-34.3 mT), in GSH and biomass production. Additionally, control experiments (CE), without the application of MF, were performed. The results indicated the existence of favourable alterations in GSH and biomass concentrations due to the application of MF. In all experiments, the amount of biomass produced was higher than in CE and, with regard to GSH yield, in all the experiments at 24 and 48 h it was higher and in three experiments at 72 h of culture. The highest specific GSH yield (20.9 mg(GSH)/g(biomass)), GSH yield (340.0 mg/L) and biomass (16.26 g/L) were obtained using a MF induction of 25.0 mT for 16 h. These results were 16.1%, 39.0% and 19.6% higher than in the CE, respectively. Through statistical analysis it was found that the MF induction was a significant factor in GSH yield, and also it was observed that, within the range of the experimental conditions used, the lower MF induction, the higher the GSH yield. (C) 2010 Elsevier Ltd. All rights reserved.