Introduction: The medical literature contains several studies showing that the response of hemodialysis patients after vaccination is inferior to that of the general population. Concerning the specific response to HBV vaccination, several additional factors contribute to an inefficient immune protection. This study was designed to investigate the possible relationship between AntiHBs titers and several factors in our population. Materials & Methods: in this cross-sectional study all of the vaccinated hemodialysis patients in Kowsar hospital of semnan were enrolled as cases. The information required to analyze the data, including age, sex, BMI, underlying disease, smoking, duration of treatment with hemodialysis and the time elapsed since the last dose of vaccination and AntiHBs titers of them through their hospital documentations were entered in checklist. Data were analyzed by the chi- square test, T test and Fishers exact test and Mann-Whitney U test. Results: In this study 79 hemodialysis vaccinated patients were studied. After data analysis it was indicated that there was no statistically significant relation between the variables and AntiHBs titer. On the other hand, the relation between AntiHBs titer and the time elapsed since the last dose of vaccination was significant (p=0.010). Conclusion: our findings indicate that in our hemodialysis center, only the time since last dose of vaccination is effective both on AntiHBs titer and immunity of patients somehow after 12 months of full vaccination there is a significant decrease in AntiHBs levels leading to losing the protective titer.