We have established a new simple and rapid screening method for glucose-6-phosphate dehydrogenase (G6PD) deficiency. The principle of this method is the formation of blue formazan with the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) produced by G6PD absorbed on a DEAE-Sephadex anion exchanger. The whole procedure is performed in a microcentrifuge tube and it can be completed in less than 30 min without any special equipment other than micropipettes. Our method is particularly suitable for field detection of G6PD-deficient subjects prior to administration of primaquine in situ.