Background: To date, 36 years has passed since the beginning of measles vaccination; the disease is still circulating around the world, threatening lives of human beings especially in developing countries. In recent years, we have confronted measles in previously vaccinated adults from all over the country. Objective: To find out if there is a need for changing our routine measles vaccination schedule. Methods: In a cross-sectional study, 241 medical students (127 males and 114 females) were randomly selected. We measured the titer of antibody against measles in their blood using ELISA. Results: Ninety-eight (40.7%) out of 241 had positive, 39 (16.2%) borderline, and 104 (43.1%) negative antibody titers. Conclusion: In this study, only 40.7% of the previously vaccinated students had positive antibody titers, while the rest remained susceptible to contract wild measles virus.