On April 5, 2022, an increase in cases of acute hepatitis of unknown etiology was reported in previously healthy children under the age of 10 in the United Kingdom. Since there is no link between these patients, called acute non-HepA-E hepatitis, and viral hepatitis agents (hepatitis A, B, C, D, and E), the possible etiology, and pathogenesis of this emergency is being investigated. One of the alarming features of this epidemic is the high requirement for liver transplantation in a fraction of the cases. In cases other than hepatitis A, B, C, D, and E, a case definition is made by looking at a series of clinical pictures, including serum transaminase levels and age. As of August 26, 2022, 513 cases of acute hepatitis have been reported in Europe and 1,010 globally. Adenovirus was detected in 75% of cases tested in the UK, but data for other countries are still lacking. The role of other etiologic agents is still under investigation. The exact disease pathogenesis has not yet clear. Evidence of human-to-human transmission of the disease remains unclear. Epidemiological studies are critical in clarifying the uncertainties regarding the existence of links between the cases reported to date. Continuing the national and international surveillance activities of the countries in an organized manner is the most basic issue required for the elimination of the epidemic.