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 < .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.