To examine HIV/AIDS knowledge, attitudes, related behaviors, and sources of HIV/AIDS information among high school-aged students in South Korea. One thousand and seventy-seven students (586 females and 491 males) from 5 high schools from 5 representative school districts participated in the survey. A self-administered questionnaire measuring knowledge (19 true-false items), attitudes (4 items, 5-point Likert-type scale), sources of information (6 items, yes/no), and sexual behaviors (8 items, yes/no) was utilized. The level of HIV/AIDS knowledge among Korean adolescents was moderate, with the mean scores of 13.93 out of 19 for males and 13.35 for females (p less than 0.01). Attitudes toward persons with HIV/AIDS were negative, with the mean scores of 3.06 for males and 3.09 for females. Of 42 respondents (4.4%) who had engaged in sexual intercourse, 18 (40%) had used condoms. Almost half of the total respondents reported they were not concerned about HIV/AIDS (46.0%), and 94.4% indicated the need for receiving HIV prevention education in the future. The respondents identified TV (52.5%) and school classes (32.1%) as the two major sources of information on HIV/AIDS. Only a few pointed to their parents (1.3%) as a source of information. This preliminary study summarizes the current status of prevention education on HIV/AIDS available in Korea and can provide implications for developing more differentiated intervention strategies specific to culture, age, and gender.