The objective of this study was to investigate the diphtheria-tetanus-pertussis and/or measles-mumps antibody titers before and after vaccination at various time points of acute lymphoblastic leukemia (ALL) therapy and to Suggest an appropriate vaccination approach for ALL patients. The authors studied 37 ALL patients and 14 healthy control subjects, divided into three groups. In group I (newly diagnosed patients), baseline anti -diphtheria, anti-tetanus, and anti-pertussis titers were determined. Patients in group 2 (on maintenance chernotherapy) and group 3 (patients not receiving therapy for 3-6 months) were vaccinated with diphtheria-tetanus with or without acellular pertussis; group 3 and control subjects were also given measles-mumps-rubella vaccine. Preimmunization and 1-month postimmunization titers were drawn. Preimmunization antidiphtheria and anti-tetanus antibody titers between the groups and the controls were statistically similar. The seropositivity rate for anti-measles antibody in group 3 was significantly lower than controls. After vaccination, all of the patients developed protective antidiphtheria and anti-tetanus antibody titers. The seroconversion rates of group 3 and controls for anti-measles and anti-mumps antibodies were statistically similar. The results showed that patients on maintenance therapy and after cessation of therapy made good antibody responses to diphtheria and tetanus toxoids, but response to measles and mumps vaccines was not as sufficient as toxoid vaccines. Children with ALL can receive the appropriate vaccines during and after maintenance treatment.