A full-length cDNA sequence encoding the precursor of a novel venom peptide (named BmKn1) with no disulfide bridge was first isolated from the venom gland cDNA library of Chinese scorpion Buthus martensii Karsch. The encoded precursor consisted of 70 amino acid residues including two parts: a signal peptide of 23 residues, and a putative mature venom peptide (BmKn1) of 47 residues. The sequence of BmKn1 showed no similarity to those of other scorpion venom peptides. BmKn1 may be the first member of a new venom peptide family from scorpion. Future research will be interesting to unravel further the pharmacological function of this novel scorpion venom peptide.