Two phospholipases A2, CM-I and CM-II, were purified from Bitis nasicornis venom by gel filtration on Sephadex G-50, followed by ion-exchange chromatography on CM-cellulose. Both enzymes comprise 119 amino acids, including 12 half-cystine residues. The primary structure of CM-II has been elucidated. The sequence and invariant amino-acid residues of CM-II resemble those of phospholipases A2 from other venoms of Viperidae and Crotalidae (Group II) snake venoms. CM-I and CM-II both contain a single histidine residue which is probably located at the active centre (histidine-47). CM-II are relatively non-toxic.