The presence of a mounting sex pheromone was demonstrated on the surface of fed female Rhipicephalus appendiculatus. This pheromone, which is present on the female cuticle, allows the male to recognise the female. The pheromone was removed by cleaning the female in hexane, resulting in the loss of male mating behaviour in in vitro experiments. Male mating behaviour was resumed when extract made from fed female cuticle was replaced on cleaned females. When the extract was transferred to innanimate objects typical male mating behaviour was released. Preliminary chemical analyses indicated that the active component of the extract was contained in the sterol ester fraction of the extract.