The recent mass immigration to Israel from the former U.S.S.R. and Ethiopia has significantly increased the hepatitis B virus (HBV) carrier rate. Since January 1992, all newborns in Israel have been routinely immunized against HBV. The same routine of vaccination has been used for premature and term newborns. The aim of the present study was to investigate the immune status against HBV in term and preterm infants at the age of 1 year. All infants were vaccinated at day 1 and at 1 and 6 months with Engerix. Hepatitis B antigen antibody (Ab) serum titers were determined at the age of 1 year. All infants had detectable Ab titers (responders); 92.5% had protective titers (> 10 mlU/ml), out of which 26.5% were low responders (< 100 mlU/ml) and 65% were high responders (> 100 mlU/ml). There was no significant difference in immune responses between term and preterm infants.