Background and aim: As acute leukemia's are characterized by abnormal proliferation of precursor cells simulating normal hematopoietic stem cells (HSC.) It is critical to isolate acute myeloid leukemia stem cells (AML LSCs) from normal HSCs in order to eradicate the AML LSC without killing normal HSCs. This can be done by identifying a molecule that is expressed or functions specifically at the AML LSC stage. This paper is aimed to investigate the role of T-cell immunoglobulin mucin-3 (TIM3) expression on leukemic stem cells of AML patients and to correlate its level with the outcome of the disease. TIM3 was assessed by Flow-cytometer technique Patients and methods: Our study included 30 patients newly diagnosis as acute myeloid leukemia between March 2016 and December 2016. Age ranged from 20 to 68 years old with median age was 32 years. Seventeen cases were males, and 13 cases were females. The Ethical and Research committees approved this study in the South Egypt Cancer Institute. An informed written consent in accordance was taken from all cases. Results: mean expression of TIM3 on CD34+ CD38- LSCs was 48.80 ± 29.70 % with range of 30% to 97% while expression of TIM3 on CD34+ CD38+ LBs was 25.29 ± 18.34 with range of 26% to 67%. Remission occurred in 18 cases (60%) based on morphologic assessment of peripheral blood and bone marrow aspirates. Patients who did not achieve complete remission had significantly higher expression of TIM3 on leukemic stem cells in comparison to those who achieved remission (64.18 ± 20.95 versus 38.55 ± 30.69. Disease-free survival was higher in those who had remission in comparison to those patients who failed to achieve remission (14 months versus 12 months). Conclusion: lower T-cell immunoglobulin mucin-3 expression may improve outcome and survival of patients with acute myeloid Leukemia but further large control study studies are recommended.