The aim of the study is to examine the epidemiology of anaphylaxis in hospitalized children in Lazio (Central Italy) and to evaluate the incidence and case fatality rate. We also verified the concordance of diagnosis between the Emergency Department and Ordinary hospitalizations. In order to obtain these results, we reviewed all ICD-9 codes indicative of anaphylaxis in all primary and secondary diagnoses from 2000 to 2003 in all Emergency Departments, Ordinary Hospitalizations and Day Hospitals in Lazio. We then identified 203 ICD-9 diagnoses of anaphylaxis in children aged between 0 and 17 years. Anaphylactic shock (995.0) accounted for 109 (53.7%) of cases. Food anaphylaxis (995.60 onwards) accounted for 87 (43.0%) of cases. Food anaphylaxis was more frequent in the first years of life. In fact, it decreased from 12.5/100,000 resident children/year in the first year of life to 6.1/100,000 resident children/year in the first two years of life, and less than 3/100,000 resident children/year after the seventh year (p <0.001). Only 12.5% of cases of anaphylaxis diagnosed in Ordinary Hospitalizations were subsequently diagnosed by the Emergency Department as anaphylaxis. Moreover, only 42.3% of the diagnoses of anaphylaxis made in the Emergency Department were later confirmed during ordinary hospitalization. In the four years of study, one child died from anaphylaxis. Thus, mortality was 0.038 cases/100,000 resident children/year. In conclusion, the incidence of hospitalization was highest in the first years of life, during which food anaphylaxis accounted for most hospitalizations. The inconsistency of diagnoses between Emergency Departments and Ordinary Hospitalizations suggests the need to increase awareness of anaphylaxis among health workers.