Purpose: This study was done to investigate internet addiction, sexual attitudes and gender egalitarianism in middle school students, and to identify the differences of sexual attitude and gender egalitarianism according to the level of internet addiction. Method: The participants were 344 students from two middle schools in Seoul. Data were collected through self-report questionnaires which included an internet addiction test, a sexual attitude scale, and a Korean gender egalitarianism scale for adolescents. The data were analyzed using the SPSS program. Results: Of the students, 63.1% reported being average on-line users, 33.4%, heavy on-line users, and 3.5%, internet addicted. Sexual attitudes and gender egalitarianism of average on-line users were different from those addicted to the internet. Internet addiction, sexual attitudes and gender egalitarianism of students were different according to general characteristics, time spent on-line, and exposure and contact to cyber obscenities. Conclusion: Sexual attitudes and gender egalitarianism in middle school students were influenced by internet addiction. Therefore nursing interventions to prevent and manage internet addiction need to be developed and provided to middle school students. Also a variety of programs for teaching sexuality to adolescents should be developed.