Abstract A mass-casualty situation (MCS) usually is short in duration and resolves itself. To minimize the risks to patients during MCS, planning is essential. This article summarizes the preparations needed at the hospital level, for a local MCS involving numerous trauma victims arriving to the Emergency Department at a short notice. Experiences and conclusions related to the implementation of the Israeli strategy in one hospital that combines the responsibilities of both the military and civilians are summarized. The Ministry of Health distributes the master MCS plan to each hospital where a local committee adapts it to the specific situation in a format of standing orders. After its approval by the Ministry of Health, an annual inspection is conducted to check the ability of the staff to manage a MCS. A full-scale drill is conducted every second year during which each site's readiness level and the continuity of the flow of care are tested. In building the strategy for treating trauma victims during a MCS, a few assumptions were taken into account. The goal of treatment in a MCS is to deliver an acceptable quality of care while preserving as many lives as is possible. In theory, the capacity of the hospital is its ability to manage a load of patients in the range of 20% of the hospital bed capacity. Planning and drilling are the ways to minimize deviations from the guidelines and to avoid management mistakes. Special attention should be paid to problems related to the initial phase of receiving the first message, outside communication, inside hospital communication, and staff recruitment. Other issues include: free access to the hospital; opening a public information center; and dealing with the media and very important persons (VIPs). A new method for creating the needed MCS plan in the hospital is suggested. It is based upon knowledge of management techniques that used multi-level documents, which are spread via Intranet between the different key figures. Using this method, it is possible to keep the strategy, the source documentation, and reasons for choosing it, as well as immediate release of checklists for each functions. This detailed, time consuming work is worthwhile in the long run, when the benefits of easy updating and better preparedness are apparent.