Introduction: Our objective was to compare the effectiveness, speed, and complication rate of the traditional manually placed intraosseous (IO) catheter to a mechanical drill-assisted IO catheter by emergency medicine (EM) resident physicians in a training environment. Methods: Twenty-one EM residents participated in a randomized prospective crossover experiment placing 2 intraosseous needles (Cook® Intraosseous Needle, Cook Medical, Bloomington, IN; and EZ-IO® Infusion System, Vidacare, San Antonio, TX). IO needles were placed in anesthetized mixed breed swine (mass range: 25 kg to 27.2 kg). The order of IO placement and puncture location (proximal tibia or distal femur) were randomly assigned. IO placement time was recorded from skin puncture until the operator felt they had achieved successful placement. We used 3 verification criteria: aspiration of marrow blood, easy infusion of 10 mL saline mixed with methylene blue, and lack of stained soft tissue extravasation. Successful placement was defined as meeting 2 out of the 3 predetermined criteria. We surveyed participants regarding previous IO experience, device preferences, and comfort levels using multiple choice, Likert scale, and visual analog scale (VAS) questions. IO completion times, VAS, and mean Likert scales were compared using Student’s t-test and success rates were compared using Fisher’s exact test with p<0.05 considered significant.Results: Drill-assisted IO needle placement was faster than manually placed IO needle placement (3.66 vs. 33.57 seconds; p=0.01). Success rates were 100% with the drill-assisted IO needle and 76.2% with the manual IO needle (p=0.04). The most common complication of the manual IO insertion was a bent needle (33.3% of attempts). Participants surveyed preferred the drill-assisted IO insertion more than the manual IO insertion (p<0.0001) and felt the drill-assisted IO was easier to place (p<0.0001).Conclusion: In an experimental swine model, drill-assisted IO needle placement was faster and had less failures than manual IO needle placement by inexperienced resident physicians. EM resident physician participants preferred the drill-assisted IO needle. [West J Emerg Med.2013;14(6):629–632.]