Background: Saudi Arabia is considered to be an area of endemic hepatitis B virus (HBV) infection. Among Saudi children, the overall HbsAg carrier rate dropped from 6.7% in 1989 to 0.3% in 1997 after mass HB vaccination program among adults prevalence is 0.22%. The prevalence varied by region, ranging from 0.03% to 0.72% with a mean incidence of 0.15%. Objectives: To determine level of knowledge about hepatitis B and its associated factors among school teachers at Al-Iskan sector in Makkah Al Mukarramah. Subjects and methods: A Cross-sectional community-based study was adopted. It included all-male school teachers in primary, intermediate and secondary stages at Al-Iskan sector in Makkah Al Mukarramah. A self-administered valid questionnaire was utilized for data collection. It included personal data, questions regarding etiology, epidemiology, symptomatology, risk factors, preventive measures and outcome of hepatitis B. Results: The research involved 137 medical students. Their age ranges among 21 and 28 years with an average of 23.0 and (±SD) of (±0.9) years. Slightly more than half of them (50.4%) were males. All students ever used Facebook and used it in the last year. Almost two-thirds of students (62.7%) checked their Facebook account daily whereas 5.1% checked it within a one-hour interval. Overall, based on the BFAS cutoff level, Facebook addiction was identified among 13 students representing 9.5% of the participants. Addiction was more reported among older students, p=0.038 and those who spent between 21 and 40% of their Facebook time on work-related issues, p=0.034. Conclusion: inadequacy of knowledge regarding HBV among teachers in Al-Iskan sector, Makkah in certain key areas of HBV. This lack of knowledge is a matter of concern since teachers could disseminate their information to young youth at schools.