Background: there is a lack of population-based studies of anaphylaxis from low-and middle-income countries. This hampers public health planning and investments and may influence availability of adrenaline auto-injectors. Objective: we conducted the first national population-based study of anaphylaxis hospitalization in Brazil. Methods: descriptive study using routinely reported data to the Brazilian Hospital Information System for the years 2011-2019. Information available is coded based on the International Classification of Diseases (ICD)-10 and covers main cause of hospitalization (primary cause) and any conditions contributing to it (secondary cause). Results: over 9 years, we identified 5716 admissions due to anaphylaxis for all causes. The average hospitalization rate related to anaphylaxis was 0.71/100,000 population per year, with a 2.4% (95% CI 1.9%, 2.9%) increase per annum over the study period. Admissions were more frequent among females (52.8%), except for cases due to insect sting. Most admissions occurred in adulthood, from 30 to 59 years (36.3%) but 13.8% in preschool children (0-4 years). There were more young children admitted for food-related anaphylaxis, and more adults admitted for drug/iatrogenic-related anaphylaxis. There were 334 cases (5.8% of admissions) of fatal anaphylaxis over the study period, with increased case fatality rate over time. Conclusions and clinical relevance: this is the first study of anaphylaxis hospital admissions using nation-wide data from a low- or middle-income country. Hospital admissions and fatalities from anaphylaxis in Brazil appear to be increasing.