Purpose: During resuscitation in emergency situations, establishing intravascular access is crucial for promptly initiating delivery of fluids, blood, blood products, and medications. In cases of emergency, when intravenous (IV) access proves unsuccessful, intraosseous (IO) access serves as a viable alternative. However, there is a notable lack of information concerning the frequency and efficacy of IO access in acute care settings. This study aims to assess the efficacy of intraosseous (IO) access in acute care settings, especially focusing on children in a level 1 trauma center., Methods: This retrospective study included patients with IO access presented in a level 1 trauma center emergency department (ED) between January 2015 and April 2020. Data regarding medication and fluid infusion was documented, and the clinical success rate was calculated., Results: Of the 109,548 patients that were admitted to the ED, 25,686 IV lines were inserted. Documentation of 188 patients of which 73 (38.8%) children was complete and used for analysis. In these 188 patients, a total of 232 IO accesses were placed. Overall, 182 patients had a functional IO access (204 needles) (88%). In children (age < 18 years) success rate was lower as compared to adults, 71-84% as compared to 94%. However, univariate regression showed no association between the percentage of functional IO access and gender, age, weight, health care location (prehospital and in hospital), anatomical position (tibia as compared to humerus) or type of injury., Conclusion: Intraosseous access demonstrates a high success rate for infusion, independent of gender, age, weight, anatomical positioning, or healthcare setting, with minimal complication rates. Caution is especially warranted for children under the age of six months, since success rate was lower., (© 2024. The Author(s).)