Background: Hepatitis B is a worldwide problem caused by hepatitis B virus (HBV). Basic Health Research 2013 estimated that there were 1, 2% of the population in Indonesia with Hepatitis, and the highest prevalence was in the East Nusa Tenggara (4, 3%). Transmission can be through vertical (perinatal) and horizontal (home contact). Aim: To analyze the risk factors for transmission at home contact from students with HBsAg reactive. Methods: On November 2015, there was a screening examination of HBsAg status with ELISA sandwich method on 341 students of Kota Kupang Senior High School and obtained 45 samples with HBsAg reactive. Continued seven months later on June 2016, 23 students were still reactive to HBsAg. After examination with HBsAg reactive, there were 89 samples of family members became respondents. The data were statistically analyzed with Chi-Square (X2) and Odds Ratio.

Results: There was no significant relationship between HBsAg status with sex and age. But, there was a significant relationship between HBsAg status with education (OR= 0,184, 95%, 0,059-0,579) and marital status (OR= 0,204, 95%, 0, 07-0,597).

Conclusion: The presence of family members with reactive HBsAg could transmit HBV to other family members. The higher education and unmarried family member could minimize the intrafamilial transmission on HBV.