The study was conducted on 60 infants bom. to Hepatitis B surface antigen (HBsAg) negative mothers. Their gestational age ranged from 32 to 40 weeks (36±2.8) and their birth weight ranged from 1250 to 3800 gm (2345±885). As¬sessment of-the. seroprotection of these infants after hepatitis B virus (HBV) vacci - nation (at 2, 4 and 6 months of age) and its relation to prematurely, birth weight and other factors on seroconversion was done. Anti-HBs antibody concentrations were measured after one month after the third vaccine dose (at 7 months of age). •Hepatitis B seroprotection could be obtained in 100% of infants with birth weight • of 1500 gm or more. Very low birth weight (VLBW) infants (< 1500 gm) seroprotec¬tion was 37.5% which is unacceptably high. Lower gestational age. sepsis, respir¬atory distress syndrome (RDS), treatment with steroids or infants had history of blood transjusion mere associated ujith poor seroprotection rates (33.32%, 33.3%. 66,7%, 66.6%, and 66.7% respectiuly). We concluded that, premature infants of birth weight