This Special Issue of Toxicon is published on the occasion of the 21st “Rencontres en Toxinologie (RT)” meeting held at the Pasteur Institute in Paris on December 9-10, 2013. More than 120 participants, from Algeria, Australia, Belgium, Brazil, Canada, Denmark, Finland, France, Germany, Ireland, Israel, Italy, Morocco, Norway, Portugal, Spain, Switzerland, Tunisia, and the United States of America, attended this meeting organized by the French Society of Toxinology (SFET, www.sfet.asso.fr). Should a reminder be appropriate, please note that the SFET missions aim at (i) promoting research in all domains concerning the venoms and toxins from animal, vegetal or microbial origins, i.e. the chemical, immunological, environmental, pharmacological, physiological domains, along with mode of action, structure-function relationships, drug-design and applicability questionings; (ii) favouring the meeting of colleagues in the field, communication to other scientists, education and training at all levels, and dissemination to more general audiences; (iii) improving fundamental research on toxinology and enhance its relevance and applications.