This study explored six health risk behaviours in a sample representing the adolescent population in Jeju, South Korea. Frequency & percentage of risk behaviours were calculated & a chi-square test explored whether differences in experimentation with risk behaviours were related to gender & schooling levels. A higher prevalence of suicide ideation was found among female students than among male students. More female students than male had made suicide plans & had attempted suicide. However, male & female students had sought medical treatment due to a suicide attempt in similar numbers. There was a greater prevalence of suicide ideation, suicide plans, suicide attempts, & medical treatments because of attempted suicide among high school than middle school students. (25 refs.)