急症室（英语：Accident & Emergency、Emergency department、Emergency room等，缩写为A&E或ER），是医院的其中一个部门。相对于有预约的门诊部，使用急症室的病人，他们的求诊需要多数是突发的，例如交通事故、中风、孕妇早产等。

急症室所处理的个案应该是「急」症，有些急症室因此设有有负责「分流」的医护人员。所有的求诊者进入急症室，都首先到分流站报到，由把关的医护人员进行检伤分类，以评估众患者的病情及先后次序，例如临危的先救，普通感冒等轻微病症的必须要排队轮候一段较长时间。

An emergency department (ED), also known as an accident & emergency department (A&E), emergency room (ER) or casualty department, is a medical treatment facility specializing in emergency medicine, the acute care of patients who present without prior appointment; either by their own means or by that of an ambulance. The emergency department is usually found in a hospital or other primary care center.