Glucose-6-phosphate dehydrogenase (G6PD) (EC 1.1.1.49) is an abundant enzyme in Saccharomyces cerevisiae. This enzyme is of great interest as an analytical reagent because it is used in a large number of quantitative assays. A strain of S. cerevisiae was genetically modified to improve G6PD production during aerobic culture. The modifications are based on cloning the G6PD sequence under the control of promoters that are upregulated by the carbon source used for yeast growth. The results showed that S. cerevisiae acquired from a commercial source and the same strain produced by aerobic cultivation under controlled conditions provided very similar G6PD. However, G6PD production by genetically modified S, cerevisiae produced very high enzyme activity and showed to be the most effective procedure to obtain glucose-6-phosphate dehydrogenase. As a consequence, the cost of producing G6PD can be significantly reduced by using strains that contain levels of G6PD up to 14-fold higher than the level of G6PD found in commercially available strains.