Background: Leishmaniasis is a parasitic disease which can manifest in various clinical forms and the visceral form is highly fatal if not treated. The drugs available are either highly costly or have poor efficacy against the parasite. Hence there is a need to find new molecules and compounds for the treatment of this disease. However, to put the new compounds in clinical trials, their toxicity and immune-modulatory effects must be ascertained to avoid harmful effects on the host. Methods & Materials: Putative immunomodulatory activity of two advanced preclinical anti-kinetoplastid candidates (KIND0001589 and KIND0001591) was evaluated, using primary human peripheral blood cells from healthy controls and kala-azar patients. Amphotericin B was used as standard drug control. The optimal concentrations of KIND0001589 (0.0134 μg/mL) and KIND0001591 (0.03 μg/mL) was used, to pre-treat the peripheral blood mononuclear cell, for 14 hours followed by addition of, PMA (25 ng/mL) and Ionomycin (1 μg/mL) for 4 hours together with Brefeldin A (1 μg/mL). Cell viability was assessed by determining the frequency of Annexin V/7AAD positive cells in CD3+, CD14+ and CD19+ leukocyte subpopulations through BD Influx FACS system. Immunophenotyping was determined in CD3+, CD4+ and CD3+, CD8+ T cells, CD14+ monocytes and CD19+ B cells. The frequency of T-cells, monocytes and B-cells expressing IFNγ, and TNF-α, respectively, was determined by the same flow cytometer. Results: Short term ex-vivo immunophenotyping assay showed KIND001589 induces CD4+TNF-α and CD4+IFNγ including IL-4, IL-10 and IL-17, in all patients. Where as KIND0001591 induced a short term immunostimulation of CD8+ T cells. Both KIND000189 and KIND0001591 highly induced CD14+ monocytes (CD14+IFNγ and CD14+TNF-α) as compared to the standard drug. KIND0001589 does not induce any B cells mediated immuno-stimulation where as KIND0001591 induced immuno-stimulation in one Patient. KIND0001589 showed stronger short term immunomodulatory activity than KIND0001591. Conclusion: Both the novel compounds (KIND0001589 and KIND0001589) were found to be safe and potential anti-kinetoplastids for animal and human trials. Funding: The study was funded from the European Community's Seventh Framework Program under the grant agreement 602773 (Project KINDReD). Immunophenotyping of whole blood from kala-azar Patient 1 Immunophenotyping of whole blood from kala-azar Patient 2 Immunophenotyping of whole blood from kala-azar Patient 3