Introduction: Intraosseous vascular access is used in medical emergencies for the application of drugs and solutions when it is not possible to establish intravenous access. The purpose of this research is to highlight the benefits of using intraosseous access in emergency situations and to point out the importance of organizing professional education and practical courses and defining the competencies of health workers working in emergency services. Objective: to examine the knowledge of health workers of the Institute of Emergency Medicine of the Republic of Croatia about intraosseous access to blood flow (IO). Methods: A total of 82 respondents participated in the research. The research was conducted in the period from April to May 2023. The respondents' knowledge was tested with a self-designed questionnaire through 10 multiple-choice questions. Results: In their practice, 45.1% of respondents used IO access to the bloodstream one or more times. 76.8% of respondents have passed theoretical and 72% practical training on IO approach at least once. 19.5% of respondents mostly agree and 18.3% completely agree that they have a sufficient level of theoretical and practical knowledge to apply IO in practice. 82% of respondents believe that more frequent training on the IO approach would increase its application in practice. On the knowledge questionnaire about IO, 40 (48.8%) respondents showed a low level of knowledge about it, 39 (47.6%) respondents had a satisfactory level of knowledge and only 3 (3.7%) respondents showed a high level of knowledge and answered 8 or more questions correctly. Respondents who have worked at ZZHM for a shorter number of years and have completed graduate studies in nursing and doctors have a higher level of knowledge about the IO approach. Respondents who underwent a greater number of practical trainings showed a higher level of knowledge about the IO approach. Conclusion: Employees of the Department of Emergency Medicine are aware of the benefits of using intraosseous access to blood flow, however, they are equally aware of the lack of knowledge and skills for its practical application. This research, as with the majority of available research, proved the need for conducting more frequent trainings on the IO approach, placing emphasis on regular practical training.