- Background Though hospitals' operational continuity is crucial, full institutional evacuation may at times be unavoidable. The study's objective was to establish criteria for discharge of patients during complete emergency evacuation and compare scope of patients suitable for discharge pre/post implementation of criteria. Basic procedures Standards for patient discharge during an evacuation were developed based on literature and disaster managers. The standards were reviewed in a two-round Delphi process. All hospitals in Israel were requested to identify inpatients' that could be released home during institutional evacuation. Potential discharges were compared in 2013–2014, before and after formulation of discharge criteria. Main findings Consensus exceeding 80% was obtained for four out of five criteria after two Delphi cycles. Average projected discharge rate before and after formulation of criteria was 34.2% and 42.9%, respectively (p < 0.001). Variance in potential dischargeable patients was 31-fold less in 2014 than in 2013 (MST = 8,452 versus MST = 264,366, respectively; p < 0.001). Differences were found between small, medium and large hospitals in mean rate of dischargeable patients: 52.1%, 41.5% and 42.2%, respectively (p = 0.001). Principle conclusions The study's findings enable to forecast the extent of patients that may be released home during full emergency evacuation of a hospital; thereby facilitating preparedness of contingency plans.