Blister beetles of the families Meloidae and Oedemeridae (Order Coleoptera, Insecta) release yellow oily droplets of haemolymph from their leg (and may be antennal) joints as a defensive measure when disturbed. The active ingredient in this exudation is cantharidin (CA). Historically, CA has been used as a chemotherapeutic agent in the traditional medicine among Asian, African and European peoples. CA, as a natural or chemically synthesized compound, is used in the modern medicine to treat various diseases. Norcantharidin is the most famous among the synthesized CA analogues and de rivatives. CA and its analogues have been applied for some dermatological cases such as warts, verruca vulgaris, corn, molluscum contagiosum and leishmaniasis. In oncology, CA and its analogues exhibit promising therapeutic effects because they induce apop tosis of human cancer cells of hepatoma, colo-rectal carcinoma, oral carcinoma, esophageal carcinoma, leukemia, bladder carcinoma, melanoma, etc. In addition, CA and its analogues have been experimentally and clinically investigated for some other diseases such as heart failure, hepatitis, neurological disorders and innate immune system. Furthermore, CA and CA -related compounds, such as Endothall and palasonin, act as a potential source of antimalarials and antihelminthics. The multi-drug resistance is one of the major obstacles in the treatment of human cancer. CA and some of its analogues have been studied as promising agent to overcome this problem. On the other hand, several drug -delivery systems have been evaluated for improving the clinical uses of CA and its analogues.