Purpose : Evaluation of HIV related knowledge among Egyptian medical students.Subjects and methods : The study involved 372 medical students of Kasr el Aini School of medicine. The study consisted of a comparative cross sectional study. The comparison is carried out between groups using a single self-administered questionnaire for both genders at first and second grades presenting preclinical knowledge compared with house officers and residents presenting post clinical knowledge.Results : In general, the study revealed a variable lack of knowledge about HIV/AIDS among students. Post clinical students demonstrated higher level of knowledge in comparison with preclinical students; this difference is statistically significant p value (0.003),it was shown in the collective data of knowledge of both groups, but in detailed groups of the questionnaire post clinical students demonstrated higher level of knowledge in comparison with preclinical students; this difference is statistically significant in G1, G2, G4, regarding HIV risk groups, modes of transmission and HIV diagnosis, while in G3 and G5 regarding HIV nature ,prevention and treatments the differences between them were statistically insignificant. Female students demonstrated a slightly higher level of knowledge in comparison with male students; this difference is statistically insignificant.Conclusion : The results of the present study revealed that Egyptian medical students have deficiencies with respect to their knowledge and amount of information received on HIV and AIDS related topics. This deficiency was more frequently observed in preclinical students than in Post clinical student.