Abstract: Monoclonal antibodies L12F7 against the target antigen of L. doreovani promastigotes were used for the detection of circulating antigen(CAg) from sera of visceral leishmaniasis pati-ents. The results showed that of 118 serum samples from visceral leishmaniasis tested. 105 were positive(88.9%). 55 normal serum samples were negative. No cross reaction with sera from patients with vivax malaria, schistosomiasis. leprosy and brucellosis, was found.The authors suggested that this assay may be used as a sensitive and new serodiagno-stic test for detecting existing infection of visceral leishmaniasis for epidemiological survey and for assessment of cure after effective treatment.