Chlorotoxin is a disulfide-rich stable peptide from the venom of the Israeli scorpion Leiurus quinquestriatus, which has potential therapeutic applications in the treatment of cancer. Chlorotoxin is the first reported high-affinity peptide blocker for small conductance chloride channels. Chlorotoxin is able to penetrate blood-brain-barrier and binds preferentially to tumor cells, making the design of therapeutics using chlorotoxin as a scaffold to treat glioma and other types of cancer of neuroectodermal origins such as melanoma, neuroblastoma, and medulloblastoma possible. To date, no obvious toxicities nor immunogenic responses after being administered to humans have been reported