Leishmania, a protozoan parasite, is the causative agent of leishmaniosis. It lives and multiplies within the harsh environment of macrophages. Infection of macrophages by the intracellular protozoan Leishman leads to downregulation of a number of macrophage innate host defense mechanisms, thereby allowing parasite survival and replication. In order to investigate how intracellular parasite manipulates the host cell environment, we undertook a quantitative study of human monocyte-derived macrophages (THP-1) following infection with L. donovani and L. major. In this study we aimed to measure the proliferation rate of human (THP1) macrophage cell line following infection with cutaneous and visceral leishmania isolates. We used sysmex to measure the proliferation rate of human (THP1) cells infected with cutaneous and visceral leishmania isolates after invitro infection of human (THP1) Macrophage cell line by leishmania isolates. We detected L. major significantly increased the proliferation of infected THP1 cell line compared with L. donvani. Our findings indicate that the infection of host cells human macrophage cell lines by L. major stimulates the replication of the cell as a mechanism to enhance the replication of the parasites.