Background: HIV/AIDS is highly prevalent among youth. Inadequate knowledge and major misconceptions related to HIV/AIDS among adolescents/youth including university students would increase its transmission. Objective: to assess knowledge about HIV/AIDS and its determinants among Assiut University students. Method: A cross-sectional study was carried out on a representative sample of 776 students in Assiut University. A multistage stratified cluster sampling technique was used. A self-administered questionnaire was used to collect data. HIV/AIDs knowledge was assessed and a knowledge score was calculated. Results: Only 70.5% of Assiut University students have heard about AIDS. The main sources of the students' knowledge were media (46.3%), internet (44.6%), school (28%), university educational courses and health education sessions (27.8%), friends (23.9%) and family (22.5%). The students in the study had a low knowledge score of 35 percent. Some misconceptions about transmission were observed such as AIDS transmission by mosquito bite (30%), hugging (19%), eating with infected person (17.5%) or being a hereditary disease (16%). Only 18% know that condoms would protect from HIV infection and 28% knew that patients could look normal without symptoms. Only 45.2% of the students knew HIV testing site. By applying Logistic regression analysis, the predictors of higher knowledge score about HIV/AIDS were being a medical faculty student, higher (fourth) grade, urban residence and family/university as sources of information. Conclusion and recommendation: University students AIDS related knowledge is inadequate. Efforts should be directed