Background: AIDS is still one of the major global health problems. The number of newly infected cases in most populations including Iranians is rising every year. The best way to prevent the increasing prevalence of the disease is to control it disease through raising the knowledge of people. This study evaluated HIV/AIDS-related knowledge among young couples attending pre-marriage counseling centers in Isfahan, Iran during 2010-11. Methods: This descriptive cross-sectional study was performed on young couples attending pre-marriage counseling centers in Isfahan, Iran. A valid and reliable self-administered anonymous questionnaire was distributed among volunteers. Total scores of couples were compared based on their demographic data (age and sex) and education levels. Data was analyzed using chi-square and Kruskal-Wallis tests and analysis of variance (ANOVA) in SPSS18. Findings: Of the 300 studied subjects with the mean age of 24.2 ± 6.3 years, 166 (55.3%) did not have a high school diploma, 83 (27.7%) had a high school diploma, 37 (12.3%) had an associate degree, and 14 (4.7%) had BSc or higher degrees. Among males, 4.7% and 33.7% had respectively good and poor levels of knowledge about AIDS. In contrast, 8.3% and 28.3% of women had respectively good and poor levels of knowledge. Chi- square test showed that women had higher knowledge than men (P = 0.01). There was a direct correlation between education and knowledge levels (P = 0.001). Conclusion: Our results showed age, gender, and education to be correlated with AIDS-related level of knowledge. Therefore, in order to increase the knowledge level, programs need to be designed to cover transmission routes and prevention methods of the disease. The role of mass media, such as broadcasting, should thus be considered. Keywords: HIV/AIDS, Knowledge level