A new variant of G6PD associated with chronic non-spherocytic haemolytic anaemia (CNSHA) in an Irish male is described. This variant is unique in that it has a normal electrophoretic mobility, Michaelis constant for G6P and NADP, and a normal pH optimum, together with a marked increase in utilisation of the substrate 2 deoxy glucose-6-phosphate. It is also relatively heat stable when compared with the normal (B) variant. These characteristics distinguish this variant from previously reported variants associated with CNSHA and we have called it G6PD Dublin.