Dental treatment procedures frequently involve blood and saliva that may be contaminated with HIV. The purpose of this cross-sectional survey was to assess Iranian dental students' knowledge of and attitudes towards HIV/AIDS patients. In 2008, a fifty-three-item self-administered questionnaire was conducted on all 750 dental students who participated in the 10(th) Dental Student Congress in Isfahan, Iran. The overall response rate to the questionnaire was 60.7 percent. The total mean knowledge and attitudes scores were 82.1 percent (excellent) and 57.4 percent (negative), respectively. There were no significant differences in the knowledge or attitude scores between male and female students. A majority of the students were aware of the association between HIV and oral candidiasis (98.1 percent), major aphthous (95.8 percent), and Kaposi's sarcoma (93.8 percent). Although a majority of the students had excellent knowledge (78.4 percent), only 1 percent had professional attitudes about treating patients with HIV/AIDS. Therefore, it is important that dental students, as future dentists, develop not only the necessary practical skills but also attitudes that will prepare them to treat HIV/AIDS patients.