注意力不足过动症（英语：Attention deficit hyperactivity disorder，ADHD）或称注意力缺失症（Attention Deficit Disorder，ADD）是一种常见的精神失调状况，目前常见的案例以儿童为主，但此类状况也会在成人身上出现。在7岁以下，约有3％至5％的儿童会出现症状。根据世界卫生组织的《世界通用疾病分类手册》第十版称此症为“过度活跃症”（Hyperkinetic Disorder），分类编号为F90，一般又俗称为「多动症」、「过动儿」、「多动障碍」。现时没有任何确切证据证实任何导致这种病症的原因，但过去曾经推测味精可能是一种诱因。但随着医学界发现成人亦患有这种病以后，这种说法便站不住脚。根据美国疾病控制及防御中心（CDC）的研究，ADHD是一个症状群的交集。因此，要正确诊断这一病症，不能依靠单一测试去确定，而必须同时采用多种测试配合去确认。

Attention deficit hyperactivity disorder (ADHD) is a psychiatric disorder of the neurodevelopmental type. It characterized by problems paying attention, excessive activity, or difficulty controlling behavior which is not appropriate for a person's age. These symptoms begin by age six to twelve, are present for more than six months, and cause problems in at least two settings (such as school, home, or recreational activities). In children, problems paying attention may result in poor school performance. Although it causes impairment, particularly in modern society, many children have a good attention span for tasks they find interesting.