AML is the most common type of acute leukemia in adults, accounting for approximately 80% of adult cases of acute leukemia. 1 AML is generally recognized as disease of late age, with first-time diagnoses of AML made at 68 years of age on average. 2 Still, children account for 6% to 7% of cases of AML and have a biology that is quite different from that of adult patients. 3The disease arises from bone marrow stem cells which proliferate uncontrollably with impaired differentiation capacity, leading Abstract Introduction: Acute myeloid leukemia (AML) is the most common acute leukemia in adults. There is growing evidence that microRNAs (miRNAs) provide prognostic information in AML. MiR-204 has a tumor suppressor function, and several studies have proven its role in solid cancers. The aim of this work is to evaluate the level of expression of miR-204 in adults newly diagnosed with AML with normal karyotype and to correlate its level of expression with disease outcome and different prognostic factors. Patients and methods: The study included 87 adult patients newly diagnosed with AML. Detection of miR-204 was done using RT-PCR in patients and seven agematched controls. Results: Acute myeloid leukemia patients showed significantly lower miR-204 expression, compared to control group (P = .029). Low miR-204 expression was significantly associated with positive CD34 (P = .017), with poor performance status (PS) (P = .009), and with the presence of diabetes mellitus (DM) (P = .014). Low expression of miR-204 was also significantly associated with shorter overall survival (OS) (P = .020) and disease-free survival (DFS) (P = .013). Low miR-204 expression was identified as an independent prognostic factor for prediction of shorter OS (P = .034) and DFS (P = .027) in AML. Conclusion: To the best of our knowledge; this is the first time to prove the correlation between miR-204 expression and CD34 expression. Further study of this correlation is needed to confirm the role of miR-204 in CD34-positive cells, including leukemic stem cells. This correlation may have therapeutic implications. MiR-204 can be used as a biomarker for PS in AML patients. K E Y W O R D S acute myeloid leukemia, CD34, leukemic stem cells, miR-204, performance status S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section. How to cite this article: Abdelhafiz AS, Elsayed GM, Saber MM, Gameel A, Hamdy N. Low expression of miR-204 is associated with expression of CD34 and poor performance status in denovo AML. Int J Lab Hematol. 2020;42:263-269.