2022年3月31日，苏格兰首先报告了5例患有不明原因重症肝炎的儿童。世界卫生组织(World Health Organization，WHO)于4月15日就不明原因儿童肝炎发布指导性意见，对确诊病例、可疑病例和流行病学相关病例进行了定义。截至4月21日，已有12个国家报告169例确诊病例，从1月龄至16岁不等。临床表现为急性肝炎，谷草转氨酶(aspartate aminotransferase，AST)或谷丙转氨酶(alanine aminotransferase，ALT)＞500 IU/L，多数患儿有黄疸、恶心、腹痛、乏力、嗜睡和胃肠道症状，包括腹泻和呕吐，大多数患儿无发热。17例接受了肝移植，至少报告1例死亡。考虑到流行病学特点和患儿的临床特征，感染性因素导致该疾病的可能性更大。病例的实验室检查结果均排除了甲、乙、丙、丁和戊型肝炎，并提示腺病毒可能与不明原因儿童肝炎有关，但其他感染性因素或环境因素仍不能完全排除。本文对此次不明原因儿童肝炎的发展情况及其可能病因进行了介绍。该疾病存在输入性风险，我国应对此早做准备。

On 31 March 2022, Scotland first reported five children with unexplained severe hepatitis. The World Health Organization (WHO) issued a guidance on April 15, defining confirmed cases, possible cases and epidemic-related cases of the unexplained hepatitis affecting children. As of April 21, 169 confirmed cases, whose ages ranged from 1 month to 16 years, had been reported in 12 countries. The clinical manifestation was acute hepatitis with aspartate aminotransferase (AST) or alanine aminotransferase (ALT) above 500 IU/L. Many cases had jaundice, nausea, abdominal pain, fatigue, sleepiness and gastrointestinal symptoms like diarrhea and vomiting. Most cases had no fever. Seventeen cases received liver transplantation and at least one death was reported. Considering the epidemiological and clinical characteristics of the cases, infectious factor(s) is more likely to be the etiology. The laboratory examination results of all cases excluded hepatitis A, B, C, D and E, while suggested adenoviruses may be related to the unexplained hepatitis in children, but other infectious factors or environmental factors cannot be completely ruled out. The present paper introduces the development and possible causes of the emerging unexplained hepatitis in children. China should be prepared to cope with an imported risk of this disease.