Background and ObjectivesPlanning transfusion needs in mass casualty events (MCE) is critical for disaster preparedness. Published data on blood component usage were analysed to seek correlative factors and usage rates.Materials and MethodsEnglish‐language medical publications since 1980 were searched for MCEs with numbers of patient admissions and transfused RBCs. Reports were excluded from natural disasters or with total RBC use <50 units. Statistical analysis employed Mann–Whitney U‐tests and Spearman's rank correlations.ResultsIn 24 reports, the average units per admission were 3·06 RBCs, 2·13 plasmas and 0·37 platelet doses. Five RBCs per admission would have sufficed for 87% of events. Transfusion needs involving bombings correlated with admissions (P ≤ 0·03). In the formula (massive‐transfusion patients in MCE) times X = (total units for all MCE patients), the average X was 35 for RBCs (correlation P = 0·01), 17 for plasma (P = 0·10) and five for platelet doses (P = 0·06). From 67% to 84% of all components used were given in the first 24 h (event medians).ConclusionsBlood component use in MCEs correlated with numbers of patients admitted or receiving massive transfusion. More current data are needed to better reflect emerging trauma care practices and refine predictive models of transfusion needs.