PURPOSE: This study aimed to assess current knowledge of and training experiences with the intraosseous (IO) line among emergency medicine (EM) and pediatric residents who care for critically ill children and to evaluate the educational effectiveness of the IO line workshop. METHODS: During May and June 2008 , a workshops on IO line insertion was held for EM and pediatric residents. The workshop comprised a 45-min lecture and a 15-min hands-on session. Asemi-drill type EZ-IO machine was used for education. Self-assessment questionnaires gauged residents knowledge of and experiences with IO line insertion or bone marrow (BM) examination and their confidence with IO line insertion before and after the workshop. Performance tests were completed for skill evaluation. RESULTS: Forty-five pediatric residents and 22 EM residents participated in the workshop. The pre-educational questionnaire revealed that EM residents had more educational experience in IO line insertion than pediatric residents (p<0.001), while pediatric residents reported more experience in BM examination (p<0.001). The post-educational questionnaire showed a statistically significant higher percentage of correct answers (p<0.001). Although the pediatric residents inserted an IO line more quickly (P=0.001), most residents (88.7%) succeeded in IO line insertion on their first attempt; there was no difference in the groups success rates. Both groups showed higher confidence in performing IO line insertion after training (p<0.001). CONCLUSION: Observed educational effectiveness in both knowledge and confidence of IO line insertion skill suggest educational opportunities for pediatric and EM residents should be increased.