Background: Acute myeloid leukemia (AML) is a complex clonal malignancy that is impacted by both environmental variables and chromosomal anomalies. High tumour load and a poor prognosis are pathologically indicated by elevated white blood cell (WBC) count and lactate dehydrogenase (LDH) values. Objective: This study aimed to assess the clinical significance and prognostic value of serum LDH levels in AML patients. Patients and methods: At the Hematology Unit, Oncology Center, Mansoura University, we performed a retrospective analysis with 40 AML patients (19 males and 21 females) with a mean age of 44.3 ± 15.1 years. Hemoglobin was 8.5 g/dL, platelet count was 32.2 x 10⁹/L, and median WBC was 31.5 x 10⁹/L. Median serum LDH was 731.5 IU/L. The eligible patients had intermediate dose Cytarabine consolidation after receiving standard-intensity induction chemotherapy. Results: AML patients exhibited significantly higher LDH levels compared to healthy controls (215 IU/L; range 107-330) (P<0.001). Higher LDH levels correlated positively with WBC count and were notably associated with age over 60 and WBC > 50×10⁹/L (P < 0.05). Patients whose LDH was higher than the median had an OS of two months, which was significantly shorter (range 1-6 months) versus 6 months (range 1-9 months) for those below the median (P=0.035). Univariable and multivariable analyses confirmed elevated LDH as a poor prognostic indicator for OS (P=0.036; HR=1.007, 95% CI, 1.005-1.011). Conclusion: High serum LDH level at diagnosis is an inexpensive, predictive marker of poor survival outcomes in patients with recently diagnosed AML, underscoring its importance in prognostic assessments.