The aim of this study was to determine the efficacy of immunization against hepatitis A and B infections with '' rapid '' or '' accelerated '' schedules in children with cancer receiving chemotherapy. Fifty-one children were recruited to receive either vaccination schedule, in the '' rapid vaccination schedule ''; hepatitis B (group I) or combined hepatitis A/B vaccines (group III) were, administered at months 0, 1, 2, and 12; in the '' accelerated vaccination schedule,'' hepatitis B (group 11) or combined hepatitis A/B (group TV) vaccines were administered on days 0, 7, 21, and 365 intramuscularly. The seroconversion rates at months 1 and 3 were 35.7 and 57.1% in group I and 25 and 18.8% in group II, respectively. Group I developed higher seroconversion rates (it month 3. In group III the seroconversion rates for hepatitis B at months 1 and 3 were 54.5 and 60% and in group IV 50 and 70%, respectively. For hepatitis A, the seroconversion, rates at Months 1 and 3 were 81.8 and 90% in group III and 80 and 88.9% in group IV, respectively. The accelerated vaccination, schedule seems to have no advantage in children receiving cancer chemotherapy except for high antibody levels at month 1. In conclusion, the accelerated vaccination schedules are not good choices for cancer patients. The combined hepatitis A/B vaccine is more effective than monovalent vaccine in cancer patients, which probably can be explained by an adjuvant effect of the antigens. The seroconversion of hepatitis A by the combined hepatitis A/B vaccination is very good in cancer patients.