BACKGROUND: The burden of hypereosinophilic syndrome (HES) in Europe is not well characterized. OBJECTIVE: To evaluate real-world patient characteristics, treatment patterns, clinical manifestations, and healthcare resource utilization for patients with HES from France, Germany, Italy, Spain, and the United Kingdom. METHODS: In this retrospective, noninterventional study, data for patients with a physician-confirmed diagnosis of HES were abstracted from medical chart reviews. Patients were aged 6 years or older at the time of HES diagnosis and had 1 or more years of follow-up from the index date (first clinic visit between January 2015 and December 2019). Data on treatment patterns, comorbidities, clinical manifestations, clinical outcomes, and healthcare resource utilization were collected from diagnosis or index date to end of follow-up. RESULTS: Data for 280 patients were abstracted from medical charts by 121 physicians treating HES, with multiple specialties. Most patients (55%) had idiopathic HES, and 24% had myeloid HES; the median number (interquartile range [IQR]) of diagnostic tests per patient was 10 (6-12). The most common comorbidities were asthma (45%) and anxiety or depression (36%). Most patients (89%) used oral corticosteroids; 64% used immunosuppressants or cytotoxic agents, and 44% used biologics. Patients had a median (IQR) of 3 clinical manifestations (1-5), most commonly constitutional (63%), lung (49%), and skin (48%). Twenty-three percent of patients experienced a flare, and 40% had a complete treatment response. Some patients (30%) were hospitalized with a median (IQR) stay of 9 days (5-15) for HES-related issues. CONCLUSION: Patients with HES across 5 European countries had a substantial disease burden despite extensive oral corticosteroids treatment, highlighting the need for additional targeted therapies.