There is a paucity of reliable data on the healthcare needs over time after sudden onset disasters (SOD). There also are no widely acknowledged definitions and data on deployment, use, staffing, and management of foreign field hospitals (FFH) after such disasters. Further, the efficiency, relevance, timing and cost-effectiveness of FFHs in the aftermath of SODs have been questioned. This was again highlighted after the 2010 Haiti earthquake, when the situation, to a large extent, was chaotic, uncoordinated, and care was not adapted to needs. These shortcomings create severe difficulties with respect to studying the real impact of medical aid after a SOD and optimizing the international medical relief efforts to be applied afterward. This article aims to present a health system approach to the deployment of FFHs after a SOD, here applied to an earthquake. By reviewing the literature and drawing on field experiences from SODs, a conceptual framework was developed that capture the essential dimensions in such a model, including: (1) classification standardization of levels of care in FFH (1–4); (2) time-phases after the event (1–5); and (3) the need for health care based on the assumed burden of disease and, hence, need for medical care in relation to the socio-economic context. The model currently is being tested on a number of international experts in the field. By using this framework, the authors hope to create: (1) a common platform for research within this area; and (2) a tool for international actors that will facilitate a development toward an international coordination body in the future. As such, the framework hopefully will offer an opening to a structural approach to the above mentioned difficulties, support international actors in their SOD preparations and deployments, and put them in a better position to optimize the resources available to the targeted population.