OBJECTIVE: To understand the dynamics underlying 'bed-blocking' in Australian public hospitals that is frequently blamed on older patients. METHODS: Analysis of primary and secondary data of utilisation patterns of hospital and aged care services by older Australians. RESULTS: A model of the dynamics at the acute-aged care interface was developed, in which the pathway into permanent high-care Residential Aged Care (RAC) is conceptualised as competing queues for available places by applicants from the hospital, the community and from within RAC facilities. The hospital effectively becomes a safety net to accommodate people with high-care needs who cannot be admitted into RAC in a timely manner. CONCLUSION: The model provides a useful tool to explore some of the issues that give rise to access-block within the public hospital system. Access-block cannot be understood by viewing the hospital system in isolation from other sectors that support the health and well-being of older Australians.