ObjectivesAcute leukemia often leads to severe complications such as febrile neutropenia. Mortality rates remain high, underscoring the need for novel prognostic markers. Regulatory T cells (Tregs) have not been extensively studied in this context.MethodsThis prospective observational, single-center study included 114 patients diagnosed with acute leukemia. Tregs percentages were measured using flow cytometry. Statistical analyses involved logistic regression to identify factors significantly associated with survival.ResultsOf the 114 patients, 78 recovered, while 36 died. The median Treg percentages were 5.9% in patients under 65 years and 5.38% in those 65 and older. A lower percentage of Tregs was associated with higher mortality in the older group (p = 0.04). Multivariate analysis highlighted the presence of comorbidities, documented infections, and day seven C-reactive protein levels as significant predictors of survival.ConclusionThis study supports the importance of monitoring chronic diseases and infection foci alongside traditional markers like C-reactive protein. Future research should explore the mechanistic roles of Tregs in immunosuppression and survival in this vulnerable population.