The past couple of decades have seen increasing concern from regulatory agencies about the toxicity of drugs, much of it justified by bitter experience with thalidomide and other drugs. In the United States concern with drug toxicity has been enhanced by the increasingly litiguous nature of society. Even rare toxicity can lead to the demise of a drug, as the recent case of Zomax™ has shown. In this environment approval of any drug with significant toxicity is difficult and the approved indications are limited. This situation makes the process of obtaining approval expensive and protracted, thereby decreasing the possibilities for a reasonable return on investment for a company seeking to market the drug. This environment does not bode well for the future of toxins as drugs.