The major phospholipase A has been purified to electrophoretic homogeneity from the venom of Vipera russelli (Russell's viper). 2. The molecular weight of the purified enzyme was estimated to be 31,000 by Sephadex G-75 gel filtration chromatography and 29,000 by SDS-polyacrylamide gel electrophoresis. The enzyme exhibited an apparent Km value of 2.3 x 10(-2) M. 3. The phospholipase A showed edema forming, indirect hemolytic and myonecrotic activities but not hemorrhagic activity.