Background: Hepatitis A is globally spread and is an important public health problem. Objectives: This study aimed at investigating the seroepidemiology of hepatitis A in students aged seven to eighteen years in Birjand, during year 2016. Methods: This study was a descriptive-analytic research, in which 300 school children aged seven to eighteen years in Birjand city were selected through the cluster sampling method. Subsequently, participants and their parents were requested to fill the questionnaire and were referred to the laboratory for blood sampling in order to examine hepatitis A antibody titer. Data were analyzed using SPSS-21 software and the chi-square test. Results: Hepatitis A antibody test was positive for only 111 out of 300 participants (37%). Females (P = 0.009) and teenagers (P = 0.0001) had significantly higher levels of antibody against HAV. There was a significant difference between the presence of hepatitis A antibody, education level of the mothers of the studied individuals (P = 0.042), and the social level and size of the family (P = 0.041). However, no difference was seen regarding fathers' literacy level (P = 0.284). Conclusions:The findings of the study showed that immunity against HAV was reduced during the past years. The reduced level of immunity against HAV along with several major risk factors for HAV infection, such as neighboring with Afghanistan and health hazards of hepatitis A for Iranian pilgrims visiting Karbala-based shrines in Iraq suggest anti-HAV vaccination as an essential priority.