Researchers have found over a quarter of female internet users have been sexually harassed online.
In the South Korean survey, 27.1% of women said they'd received sexual content or been forced into sexual conversations on the net.
Just under a fifth of men complained of similar harassment on-line in the Korean Institue of Criminology survey.
Around a quarter of men and nearly 30% of women say they've been insulted by the opposite sex, usually in chat rooms or game sites, The Korea Herald reports.
Manager of the Report Centre of Cyber Sexual Violence Lee Kyung-hwa said: "In cyberspace, sexual violence usually occurs in words and the identity of the criminal is often unknown, which encourages them to commit more serious crimes."