Aim: To determine Hepatitis B vaccination rate and determining factors for health care workers (HCWs) at AKUHN. Design: Cross sectional analytical study Study subjects and setting: Aga Khan University Hospital-Nairobi, is a 254 bed tertiary hospital, with 815 HCWs with occupational risk of infection with hepatitis B virus (HBV). The hospital has a HCW vaccination policy and vaccine available to HCWs as part of medical scheme Methodology: Two hundred and sixty six (266) eligible HCWs of all cadres were stratified then randomly recruited after giving informed consent. A questionnaire was then administered to assess knowledge, attitude and practice towards HBV infection, risk of infection, vaccination status and reasons for non vaccination. The analysis included vaccination rate, association between knowledge, attitude and practice with vaccination rates and reasons for non vaccination. Results: The hepatitis B vaccination rate is 56.01%. More than 95.5% of the HCWs know about hepatitis B, more than 86.8% know the routes of transmission. There is an association between knowledge of Hepatitis B and vaccination status (p=0.01). Fifty three percent (53%) of the non vaccinated HCWs either didn‟t know the need or procedure for vaccination, while 19.6% were concerned about side effects and costs of vaccination. Conclusion: The vaccination rate is low and efforts should be put in place to educate the HCWs on vaccination, offer reassurance on the safety of the vaccines and maintain updated vaccination records.