Purpose: This study was conducted to investigate the relationship between short message service and social media use, and sexual intercourse of high school students in Cambodia. Methods: Four hundred and eighty-three high school students from three schools in rural provinces were interviewed with structured questionnaires. Results: Sexual intercourse was found significantly more frequent among male students than among female students (p=.001), among alcohol drinkers than among non-drinkers (p<.001), among those who were not taking pictures with mobile phones than among those who were (p=.045), and among those who were exchanging SMS between boyfriend and girlfriend than among those who were not (p=.006). The students who were sending SMS by mobile phones were 5.83 times as likely to have sexual intercourse as their counterparts (p=.020), who were taking pictures with mobile phone were 0.04 times as likely as those who were not (p=.045) and the odds ratio was 15.19 times as high in alcohol drinkers as in non-drinkers (p=.001). Conclusions: Efforts should be made to encourage positive and effective use of social media among adolescents to maintain their sexual health.