摘要:Background: Assessing the prevalence of infections, which are preventable by vaccination, is crucial to monitor the vaccination program efficacy, and it can demonstrate the gaps in population immunity. The current study attempted to assess the specific Immunoglobulin (IgG) antibody against measles, mumps, and rubella (MMR) in Iranian children and adolescents, years after their vaccination. Methods: This cross-sectional study was conducted in Iran. Serum samples of 2100 students, aged 7-18 years, included in a national health survey, were tested for MMR antibodies by ELISA assay. Multistage random cluster sampling was used to select subjects from 30 provinces in Iran. Results: Overall, 1871, 1718, and 1678 serums were tested for measles, mumps, and rubella antibodies, respectively. The prevalence of positive test was 1231 (65.8%) for measles, 1327 (77.2%) for mumps and 1344 (80.1%) for rubella. Conclusion: Despite high vaccination coverage in Iran, IgG antibody against measles, mumps, and rubella was not detected in a considerable proportion of children and adolescents aged 7-18 years. In case of contacts with residents of other countries, where measles or rubella have not yet been eliminated, it may create problems for Iranian children.