Kale- azar is known as an endemic doses in some areas of Cars province ( in South) and Ardabil province ( in North- west) of Iran. In other provinces the disease has been reported, mostly, in sporadic from. However since 1949 when the first case of kale- azar was reported in Mazandaran province, to the end of 1993 more than 4300 cases had been diagnosed in at least 113 cities and districts. Kale-azar in Iran is of Mediterranean type and the causative agent is leishmania infantum. Phlebotomus major, Ph. Kandelakii and pH. Perfiliewi that have been found infected with promastigotes in the endemic areas are most probably the main vectors of the disease. Dog is the main reservoir in the endemic areas. Jackals and foxes have also been infected with leishmania in the endemic areas as well as in some other areas of Iran where kale- azar cases have been found in sporadic from. ℅ 15 to 20℅ of the dogs in Meshkinshahr and Germi from the province of Ardabil have been sero- positive also parasitic examinations in most of these cases reveals amastigotes in spleen and liver of these dogs. Recently, gray hamster has been found viscerally infected with leishmania in the Meshkinshahr, kala, azar endemic areas. The disease occurs mostly in children. In the endemic areas of Ardabil and Fats provinces 93.4℅ and 99.3℅ of the cases were found in children of <_12 years old and the highest number of cases were 53.3℅ and 54.4℅ in age group of 1_2 years, respectively . Male or female ratio in Ardabil and Fats provinces were 1.34 and 1.37, respectively. However in serological surveys of kale-azar, sero-positive rates(SPR) in both direct agglutination ( DAT) and indirect fluorescent antibody ( IFAT) tests were higher in females than males. Serological tests such as IFAT, ELISA and recently DAT have been applied in sero-diagnosis and sero-epidemiological surveys of visceral leishmaniasis( VL) in man and animal reservoirs in Iran with satisfactory results. In fact the rapid increase of the incidence of VL in Iran, during recent years, particularly, in the Kala- azar endemic areas is mainly due to increase in application of such serological techniques which in comparison to parasitological methods are more sensitive and quite specific and practical. The DAT among selorogical tests applied in Iran is a simple as well as a reliable test. In the suspected Kala- azar pediatric patients from the endemic areas , a positive DAT result along with clinical symptoms could be considered as a good indication for specific treatment of the disease.