Abstract : In Iraq, The glucose-6-phosphate dehydrogenase gene is an x-linked disease, and its deficiency is common throughout the world. This study was conducted to purify Glucose 6-phosphate dehydrogenase from favism patients and determination [Km, Vmax], and study the effect of optimum temperature, substrate, PH for G6pd in patient and control, the ongoing review presumed that the ideal pH of the enzymatic concentrate was in the reach [8-8.4]. the chemical has the most elevated compelling enzymatic at 8.5 pH for patients. The temperature of protein was steady to 37 ºC for patients and apparently exhibited the most elevated at 40 ºC. The constants were; for Michaelis-Menten of substrate [G6P] and the Vmax were [0.42mM] [27.17UI/ml] for patients and [0.142mM] and [79.36UI\ml] for control respectively.