We propose an intraosseous (IO) procedure scale for evaluating the insertion process during simulation. A 12-item scale for assessing the performance of IO insertion into the proximal tibia reproduces all the steps of a manual procedure. The performance of 31 emergency physicians was evaluated with this scale on a mannequin simulating a decompensated shock in a 6-month-old infant.Our IO procedure scale was reliable, with a very high interobserver reproducibility. The application of this scale to procedures yielded higher scores for successful than for unsuccessful procedures (P < 10), a 93.5% success rate, and a mean placement time of 2 minutes 23 seconds. Although designed for a manual insertion of an IO needle during simulation, this scale may be also suitable for use in clinical settings.