Seventy-seven patients with acute lymphoblastic leukemia (ALL) who were in complete remission and whose therapies had been stopped for at least 6 months before enrollment in this study were retrospectively analyzed regarding their antibody status for measles, mumps, and rubella, with the aim to demonstrate the seropositivity rate after treatment in the authors' group. Each patient's serum samples were analyzed by enzyme-linked immunosorbent assay (ELISA) method to determine the antibody titers before and after immunization. Measles serology was available in 77 children; 45 (58%) were seronegative. Initial ages of measle-seronegative patients were statistically lower than those of seropositive cases (median 3.29 versus 4.91 years, respectively). Mumps serology was available in 76 children; 36 (47%) were seronegative. Mumps-seropositive cases tended to have more frequent previous history of infection than seronegative cases (55.0% versus 28.6%, respectively, P=.05). Rubella serology was available in 76 children, and 20 (26.3%) were seronegative. It was determined that initial ages of rubella-seronegative patients were statistically lower than those of seropositive cases (median 3.03 versus 4.32 years, respectively). The authors concluded based on the results of their study that at a median of 3.31 years after completion of chemotherapy for ALL, the majority of cases had antibody levels lower than protective values for measles (58.4%); however, these values were 47.3% for mumps and 26.3% for rubella. Seroconversion rates after measles (55%) and mumps vaccination (57.1%) were still low. However, in the available cases, relatively adequate response to rubella vaccination (92.3%) was observed.