Background:  Hepatitis B virus (HBV) vaccination is mandatory among health care workers due to high risk of exposure to infection. However, the long-term protective effect of HBV vaccine and assessment of HBV vaccination status by measuring HBsAb remain questionable. Aim: assess the protective levels of anti-HBsAb among previously vaccinated medical residents and its relation to duration and doses of vaccine.  Methods: Cross section study conducted on 202 residents working in Kasr Al-Aini Medical hospital (single center) HBV vaccinated. Serum HBsAb titer was tested using Elecsys® Anti-HBs II reagent by automated COBAS device system e-601. The residents were classified according to their protective antibody titer into three groups; negative protective titer (< 10IU/L), positive low protective titer (10-100 IU/L) and high positive protective titer (> 100 IU/L) groups. Results: Only 9.4% had negative protective titer, 35.15% had positive low protective titer and 55.45% had positive high protective titer. Negative protective HBsAb titer was significantly higher in males (15.5%), smokers (26.5%), with incomplete vaccination schedule (26.6%), compulsory vaccinated (53%) and last vaccine dose >10years (60.7%). Multivariate logistic regression analysis revealed that the duration since last vaccination dose (<10years) and completion of vaccination schedule (≥3doses) are the significant independent factors for HBsAb protective levels with p value <0.001 and 0.012. Conclusions: Protective anti-HBsAb level is related to the number of years elapsed since vaccination and the number of vaccine doses.