Abstract: Since 1968, kala azar has been found sporadically in Meiyaogou, Turfan County, Xinjiang Uygur Autonomous Region. Four species of sandflies, Phlebotomus alexandri, Ph. mongolensis, Sergentomyia turfanensis and S. minutus sinkiangensis were collected in this area from May to August of 1983. Ph. alexandri is the predominant species, amounting 81.1% (7,716/8,843) of sandfly collected and is the only anthropophilic species. After being fed on cotton rat or hamster infected with Leishmania donovani, 93.9% (230/245) of Ph. alexandri were infected in which promastigotes not only developed in the stomach but also invaded the pharynx, buccal cavity and proboscis. A total of 643 females of Ph. alexandri collected in wild and houses was dissected and 13 (2.0%) were found naturally infected with promastigotes. The distribution of promastigotes in natural infection was similar to that in experimental infection. All the Chinese hamsters and golden hamsters inoculated with 7 isolates of promastigotes from naturally infected sandflies developed visceral leishmaniasis. In addition, golden hamster was infected experimentally by the bite of Ph. alexandri which had been infected with promastigotes of L. donovani. This is the first time to demonstrate that one species of Paraphlebotomus is playing a role in the transmission of kala azar in the Old World.