Children with cancer rare at art increased risk of hepatitis B infection and chronic liver disease. Since hepatitis B vaccines containing pre-S2 antigen has been recently reported as being more efficient in providing immunizalion in healthy individuals, the authors compared antibody response to Pre-S2-containing vaccine with no-pre-S2-containing hepatitis B vaccine, when given in double doses to 100 children receiving chemotherapy. Patients, aged 1 to 16 years with negative HBV serology, were vaccinated with 2 different types of HBV vaccines between 1997 and 1999. Group 1 received Gem Hevac B containing pre-S2 (n = 41) in a dose of 20 mug for patients younger than 10 years old and 40 mug for older patients. Group 2 was vaccinated at the same dose with hepatitis B vaccines not containing pre-S2 antigen. All vaccinations were repeated at 0, 1, and 6 months. So urn samples were drawn for determination of anti-HBs titers at 1, 3, 6, and 8 months. After the third dose of vaccine, the seroconversion rate was 72% in group 1 and 62% in group 2. The anti-HBs levels were higher in the group receiving pre-S2-containing hepatitis B vaccine. However, the difference between groups was not statistically significant (p > .05). The administration of pre-S2-containing hepatitis B vaccines may give a better seroconversion and higher antibody response to vaccination in children with cancer: But a further large-scale study is needed to confirm this finding.