Research into the pharmacology of individual cannabinoids that began in the 1940s, several decades after the presence of a cannabinoid was first detected in cannabis, is concisely reviewed. Also described is how this pharmacological research led to the discovery of cannabinoid CB₁ and CB₂ receptors and of endogenous ligands for these receptors, to the development of CB₁‐ and CB₂‐selective agonists and antagonists and to the realization that the endogenous cannabinoid system has significant roles in both health and disease, and that drugs which mimic, augment or block the actions of endogenously released cannabinoids must have important therapeutic applications. Some goals for future research are identified.

British Journal of Pharmacology (2006) 147, S163–S171. doi:10.1038/sj.bjp.0706406