Hepatits B is a big public health problem. It is a second carcinogen after tobacco. It is transmitted by direct blood contact as well as sexuall contact. Under greater risk of getting diseases are heterosexual persons with multiple sexual partners, homosexual men, intravenous addicts of narcotic drugs, newborns of HbsAg positive mothers as well as health care workers because of constant contact with patient's blood. The safest way of preventing professional infection of health care workers by any infection that is transmitted through blood, HBV included, is to prevent the exposure to blood. Today there is effective vaccine thanks to which is decreased incidence of HBV diseases. Since 1994. in Croatia all the health care workers must be vaccinated, and since 2007. all the newborns are vaccinated as soon as they were born. It is very important to get an education about HBV, closely cooperate with health care workers and take care about yourself in order to maintain health.