objective: Leishmaniasis is a parasitic disease transmitted by the bite of the phlebotomine female sand fly. Currently, no reported effective vaccines are available for the treatment of leishmaniasis; consequently, restricting this disease completely depends on controlling its transmission. Mitogen-activated protein (MAP) kinases have been reported to be involved in the regulation of the flagellum length and hence play an important role in disease transmission, especially the MAPK3 protein. Therefore, the current work focused on identifying approved drugs that can inhibit the MAPK3 protein. methods: First, the recombinant plasmid (pET28b(?+) MAPK3) was cloned into E. coli strain BL21 using the heatshock method. Afterward, E. coli was induced using IPTG, and cells were harvested for protein purification in the next step. After that, the MAPK3 protein was purified using Ni-NTA column. Then, the inhibition kinase activity of the purified MAPK3 protein was performed using an ADP-Glo Kinase Assay kit. Furthermore, the cytotoxicity of Leishmania cells were detected by alamarBlue Cell Viability Reagent. Finally, the binding affinity within the binding site of MAPK3 protein was performed by computational methods. results: Purification of the MAPK3 protein was done using an Ni-NTA column and a protein band was identified at the expected 44?kDa molecular weight. Afterward, the ability of commercial drugs (afatinib and lapatinib) to inhibit the purified MAPK3 kinase activity was performed using an ADP-Glo Kinase Assay kit. The half-maximal inhibitory concentrations (IC) of two drugs inhibited the MAPK3 protein within the same range of IC values (3.27 and 2.22?μM for afatinib and lapatinib, respectively). Furthermore, the cytotoxicity assay of compounds toward the extracellular promastigote and intracellular amastigote stages was investigated using alamarBlue Cell Viability Reagent. The results showed that both drugs were more efficient against extracellular promastigotes and intracellular amastigotes of both Leishmania donovani and Leishmania martiniquensis. Finally, the molecular dynamics simulation (MD) was performed to study the intermolecular interactions of both drugs with MAPK3 protein. From 100?ns molecular dynamics simulation, the structural stability of both drugs in a complex with MAPK3 was quite stable. conclusions: This work was suggesting that afatinib and lapatinib act as MAPK3 inhibitors and might be developed for leishmaniasis treatment.