The major role of glucose-6-phosphate dehydrogenase (G6PD) is to generate reduced nicotinamide adenine dinucleotide phosphate (NADPH), which is indispensable to reductive metabolism and maintenance of cellular redox homeostasis. Most advances in this field have been made in the pathophysiology of G6PD-deficient erythrocytes and the molecular characterization of different G6PD variants. Recently, numerous studies have shown the importance of G6PD in cell growth, development and disease progression.