Background: The discovery of biomarkers to predict the development of complications associated with hematopoietic stem cell transplantation (HSCT) offers a potential avenue for the early identification and treatment of these life-threatening consequences. Serum lactate dehydrogenase (sLDH) has been identified as a potential biomarker for determining the outcome of allogenic HSCT (allo-HSCT). Methods: A retrospective study was performed using data collected from 204 allo-HSCT recipient patients to examine the predictive value of sLDH levels pre-and post-allo-HSCT on patient survival, graft-versushost-disease (GVHD) incidence, and time to platelet/white blood cells (WBC) engraftment. Results: Our findings show that neither pre-(p= 0. 61) nor post-transplantation (p= 0. 55) sLDH levels were associated with GVHD incidence. However, elevated sLDH levels pre-and post-transplantation (≥,386 and ≥,409 IU/mL, respectively) were found to be adverse risk factors for patient survival (p= 0. 16, p= 0. 20, respectively). Furthermore, a median sLDH level≥,400 IU/mL from day +5 to day +15 post-transplantation had a significant positive association with enhanced time to platelet and white blood cell (WBC) engraftment, compared to patients with sLDH levels < 400 IU/mL (p< 0. 001). Conclusions: Our data suggests that high sLDH levels pre-and post-allo-HSCT could be considered a predictor of poor patient survival. Furthermore, high levels of sLDH days 5-15 post-allo-HSCT could be associated with improved time to platelet and WBC engraftment,however, this appears to come at the cost of increased mortality risk.