Background: hepatitis Virus B is a major health problem in Kingdom of Saudi Arabia (KSA) as it is one of the most endemicity countries for being hepatitis B seropositive. Objectives: evaluation of the knowledge, attitude and practice (KAP) of Saudi population toward hepatitis B infection in KSA.        Methods: a descriptive cross sectional study was conducted among 890 Saudi subjects aged between 20-50 years old. All participants were interviewed during the period from February 2017 till June 2017 and filled-up a predesigned validated questionnaire that consisted of 4 parts including the demographics and KAP. Results: out of the 890 Saudi subjects, 69.3% were females, 48.3% were working, 77% had college degree and 50.9% of them aged from 20-30 years old. The prevalence of hepatitis B among the studied population sample showed that only 8% of subjects declared that they had hepatitis B infection. Most of the participants had good knowledge regarding the means of HB transmission, the definition, symptoms and effects of the disease. The attitude of subjects was good in 60% but the level of practice was poor among 66% of subjects as most of subjects hadn't been screened or vaccinated for hepatitis B infection. Conclusion: the level of KAP toward hepatitis B was good in 56% of subjects with high scores of good knowledge and attitude but with poor practice levels among most of the subjects.