There is significant debate on the nature of the active therapeutic ingredient in homeopathic medicines and whether the effect of homeopathic medicines is exerted locally. This paper accepts that there is an active therapeutic ingredient in homeopathic medicines that acts pharmacologically in the body and proposes a possible receptor site.The vomeronasal organ (Jacobson's organ) is the receptor site for the detection of non-odorant molecules, eg pheromones, in reptiles, amphibians and mammals. The organ forms the main part of a chemoreceptor system known as the vomeronasal system. This paper proposes that it is this system that constitutes the receptor for homeopathic medicines in both animal and human subjects.