Poisons are widespread in plants and animals and humankind has often tried to turn them to its own advantage. Owing to their poisonous properties, some species of Strychnos genus have been employed mainly in hunting and fishing, as an adjunct to weapons used not only in the search of food and clothes, but also for preventing depredation by wild animals. They have been employed for martial and criminal purposes and also as a means of determining guilt or innocence. By their nature, poisons such as strychnine and curare affect the functioning of the victim's body; this also means that they have been, and are, an important source of pharmacological tools and medicines all over the world. With such potentially dangerous substances, care in medication is essential to avoid complications by overdose. All these points are approached in the present review.