Bleeding is a common clinical emergency that requires urgent medical attention. There is a general clinical interest in haemorrhages, which is increasing due to the recent introduction of new oral anti-coagulant drugs. Data about the incidence of bleeding in Emergency Room (ER) are lacking in literature, even if several studies report emergency admissions for haemorrhages associated with specific drugs or apparatuses. The retrospective observational study Haemorrhagic Adverse Reactions in Emergency Room (HARER) was designed in order to estimate the incidence of bleeding events and the incidence of suspected haemorrhagic adverse drug reactions as causes of Emergency Room visits. HARER takes into consideration the computerized medical records from two Emergency Departments of the University Hospital in Verona (Italy) from 2015 to 2016 over a twelve month period. According to a validated list available in literature, patients aged ≥ 18 years with an International Classification of Diseases, 9th Revision (ICD-9) diagnosis code at admission related to haemorrhage, but not caused by traumatic events, were included in the study. Unique identification code of the patient with a bleeding episode (as anonymization procedure), date of birth, gender, ICD-9 code, diagnosis at admission, complete patient’s medical history and outcome were recorded. Data were extrapolated from the First Aid database, which contains evaluation at admission, medical history, concomitant pharmacological treatment, descriptive discharge diagnosis, its corresponding ICD-9 CM code and outcome.Haemorrhages were classified into 5 groups: cerebral haemorrhage, gastrointestinal bleeding, epistaxis, haematuria and other haemorrhages.Drugs known to beassociated with haemorrhagic events were grouped into six categories:anticoagulants, antiplatelet drugs, heparins, SSRIs and NSAIDs, and we considered suspected haemorrhagic ADEs in all patient records reporting at least one of these drugs.