Introduction: This study was designed to investigate the effect of oral HSV-1 shedding on the survival of allogeneic hematopoietic stem cell transplanted (allo-HSCT) patients. Methods: One hundred nineteen allo-HSCT patients were included in the study and divided in three groups: before transplant, 100 days after transplant and 1 year of allo-HSCT. Healthy volunteers matched by age and gender were also selected. Oral swabs were performed and the nested PCR was used to detect HSV-1 presence in the oral mucosa. In statistical analysis, chi-square test was used to test the distribution of HSV1 shedding among the three groups. Time to death after allo-HSCT was displayed by means of the Kaplan-Meier method and the results were compared by the log-rank test. Cox proportional hazards multivariate model was used to evaluate the survival. Results: We observed that HSV-1 shedding was similar at different points after allo-HSCT. However, HSV-1 shedding before allo-HSCT was associated with worst survival rates after allo-HSCT in multivariate analysis. Conclusion: Our data demonstrates that HSV-1 shedding in oral mucosa before transplant is associated with worst survival rate of allo-HSCT patients.