Etiologies of acute viral hepatitis in high-income countries change with migration of populations, lifestyle changes, and emergence of new pathogens. We analyzed etiologies, characteristics, and outcomes of patients with acute viral hepatitis at a tertiary hospital in Spain.We analyzed data from all patients with acute hepatitis (n=100; 71% male; median age, 42 years; 72% Spanish nationals), older than 16 years, diagnosed in the emergency department of an academic hospital in Barcelona, Spain, from January 2014 through December 2018. Blood samples were collected and patients with serum levels of alanine aminotransferase more than 10-fold the upper limit of normal and markers viral infection were considered to have acute viral hepatitis. We collected clinical information from patients, and samples were analyzed for IgM antibody to hepatitis B (HB) core antigen, HB surface antigen, antibody against hepatitis C virus (HCV), HCV RNA, IgM against hepatitis E virus (HEV), HEV RNA, and IgM against hepatitis A virus (HAV). Patients were followed until resolution of infections or evidence of chronic infection.The most common etiologies of acute hepatitis were HBV infection (28%), HEV infection (18%), HCV infection (17%), and HAV infection (14%). The main risk factors of the cohort were sexual risk contact and intravenous drug use; 79% of cases of HAV had sexual risk behavior. Twenty-nine percent of patients with acute HAV infection and 29% of patients with HBV infection were immigrants to Spain. Fifty-four patients were hospitalized; jaundice and HCV infection were associated with hospital admission. Three patients died (2 from acute liver failure related to acute HBV infection or HBV and HDV co-infection). Chronic infections developed in 5/28 patients (18%) with acute HBV infection and 7/17 patients (41%) with acute HCV infection.Despite universal vaccination against HBV in Spain, HBV remains the most frequent cause of acute viral hepatitis in our emergency department. Almost one-third of cases of acute HBV and HAV infections were immigrants, possibly from countries with suboptimal vaccination programs. A high proportion of patients with acute hepatitis have HEV infection (18%); acute HAV infection was associated with sexual risk behavior.