Abstract: Objective To explore human immunodeficiency virus/acquired immunodeficiency syndrome(HIV/AIDS) related knowledge,attitude and behaviors among middle school students and to provide scientific basis for conducting health education on HIV/AIDS among the students.Methods With stratified cluster sampling,1 186 students from 2 middle schools in Dalian city were investigated with a self-designed questionnaire on knowledge,attitude and behaviors about HIV/AIDS.Results The awareness rate of HIV/AIDS related knowledge in the students was 37.3％-98.2％.The HIV/AIDS related knowledge score of the students was 8.61±0.79.Students in senior high school had a higher score than those in junior high school(9.19±0.78 vs 7.91±0.84,t=2.75;P<0.05).There were no statistically significant differences in the score between male and female students.Most students had a positive attitude towards AIDS patients.The HIV/AIDS related attitude score of the students was 17.87±2.34.Students in senior high school had a higher score of the attitude than those in junior high school(19.54±2.27 vs 16.33±2.04,t=3.01;P<0.05) and the male students had lower score than female students(17.03±1.94 vs 19.01±2.19,t=2.31;P<0.05).No correlation was found between HIV/AIDS related knowledge score and attitude score(r=0.11,P>0.05).Conclusion The awareness rate of HIV/AIDS related knowledge is low for middle school students and there are some discrimination and concerns against AIDS patients in some students.It is urgent to conduct specific health education on HIV/AIDS in middle school students.