A new protein,nominated as SSmp d,has been purified from the water extract of Scolopendra subspinipes mutilans L.Koch. The fraction cotaining SSmp d was separatied from the extract by gel filtration on a Sephadex G 25 column,followed by preparative isoelectric focusing.The new protein purified from the fraction by gel filtration on a Sephadex G 150 column,subsequently on a Sephadex G 100 column,and finally by HPLC on a Protein Pak TM 125 column showed a state of homogeneity on HPLC and IEF PAGE.The isoelectric point of SSmp d determined by IEF HPCE is pH 9 27.Its molecular weight was estimated to be about 24 6 kD by HPLC. Amino acid analysis of SSmp d showed that it was rich in Ala and Leu.Eleven amino acids of the N terminal sequence determined by Edman degradation were proved to be NH + 3 Asp Val Asn Phe Arg Leu Ser Gly Ala Asp Pro.