The ability of the sand fly Phlebotomus (Adlerius) arabicus to transmit Leishmania tropica was studied experimentally using hyraxes (Procavia capensis), natural reservoir hosts of the parasite. Sand flies became infected with L. tropica after feeding on a lesion of needle-inoculated hyrax. Moreover, P. arabicus fed with L. tropica promastigotes transmitted the parasite to hyraxes by bite during a second bloodmeal. Although the animals remained asymptomatic after infective sand fly bite, they were PCR positive and infectious for naive sand flies. We have thus demonstrated cyclical transmission of L. tropica by P. arabicus in hyraxes. This confirms experimentally the vectorial competence of P. (Adlerius) arabicus, and demonstrates that asymptomatic reservoir hosts are infectious to appropriate vectors.