In a prospective study conducted in Mymensingh district of Bangladesh, 1, 273 patients were assessed for the presence of visceral leishmaniasis (VL). Sodium antimony gluconate (SAG) was successfully administered to 715 patients with parasitologically confirmed infection. In the remaining 558, although there was clinical indication of VL, Leishmania donovani parasites could not be demonstrated. Administration of SAG in this group was on the grounds of the prevailing symptoms, exclusion of malaria and a positive direct agglutination test (DAT). Significant improvements in the clinical and hematological parameters were observed in 547 (98%) of the unconfirmed VL cases. On the basis of the parasitological findings or positive response to specific anti-Leishmania chemotherapy, the sensitivity and specificity of the DAT were 99.6% and 97.7% respectively. The results supported the reliability of DAT for diagnosis of VL at levels below that of parasitological detection.