Abstract: Big gerbil (Rhombomys opimus) infected with Leishmania gerbilli Wang, Qu Guan, 1964 has been found successively in the desert area of Gansu Province, Xinjiang Urgur Autonomous Region and Nei Monggol Autonomous Region. The results of epidemiological survey and experimental study of the parasite concerned were compared with the morphology, virulence, vector species and immunology of Leishmania tropica major isolated from the Middle East and reported by Soviet authors. It was suggested that L. tropica major and L. gerbilli might coexist in big gerbils in Turkmenia and Uzbekstan, USSR. L. gerbilli is noninfective to mice, golden hamsters and human beings, while L. tropica major is highly pathogenic. The main sandfly-vector of L. tropica major is Phlebotomus papatasi, but the main sandfly-vectors of L. gerbilli belong to Paraphlebotomus group such as Ph. mongolensis, Ph. caucasicus and Ph. andrejevi. Up to the present, none of zoonotic cutaneous leishmaniasis has been reported from China and Mongolia, where Ph. papatasi is not found. It is inferred that in desert areas of Turkmenia and Uzbekstan of Soviet Union, presumably Iran and Afghanistan as well, L. gerbilli coexists with L. tropica major, while in China and Mongolia L. gerbilli stands alone.