Immunochromatographic tests based on the recombinant antigen K39 represent a major advance in diagnosing visceral leishmaniasis (VL) in recent years. Some performance variations are expected and have occurred in the use of several commercial rapid tests, especially in different geographical settings. This is the first evaluation in the Americas of the test recently provided by the public health system in Brazil for the diagnostic of VL, the OnSite™ Leishmania IgG/IgM Combo. In this first clinical test evaluation, 113 VL-positive patient samples and 73 negative controls were tested and a sensitivity of 91.2% and specificity of 94.5% were observed. These results indicate the need for further analysis and comparisons with the performance of other available commercial tests in order to define the impact of this new test on the quality of VL diagnosis in Brazil.