<p>This study investigated the effectiveness of group discussion added to a threat appeal-based educational intervention for young cyclists.　Its purpose was to reduce the use of mobile phones while bicycle riding.　Sixty-one young cyclists were assigned to either a control group that participated in a threat appeal-based educational intervention without a group discussion （n = 31） or an experimental group （n = 30） that participated in an intervention combined with group discussion.　All participants completed questionnaires immediately pre- and post-intervention, and again after approximately three months.　Results showed that self-reported frequency of mobile phone use during bicycle riding decreased after the intervention in both groups.　The attitude towards the use of mobile phones while bicycle riding became significantly more negative after the trial in both groups, but the effect did not last for three months in the control group.　The intention to refrain from using mobile phones while bicycle riding after the intervention increased only in the experimental group, and this effect lasted for three months.　These results suggest that combining group discussion is an effective way to encourage young cyclists to refrain from using mobile phone while bicycle riding through a threat appeal-based intervention.</p>