Three Masai children from Kekonyokie South Location, Kajiado District were diagnose with visceral leishmaniasis (kala-azar). Leishmanial isolates from the patients were characterized as Leishman a donovani sensu lato, by cellulose acetate electorphoresis. Case histories indicated that the disease was acquired locally. A survey of 409 children at 7 local primary schools and one nursery school revealed no additional case. Sandfly surveys using light traps and sticky paper traps recovered 10 species of sandfly, including 2 Phlebotomus species. P. martini was prevalent throughout.the area. P. orientalis was only rarely encountered, but it was the first collection record of this species in the southern portion of the Rift Valley in Kenya. Although no Leishmania-infected sandfly was found, P. martini is probably the vector of kala-azar in the location, as it