The diagnosis of deep venous thrombosis (DVT) in patients presenting to the emergency department (ED) has traditionally been limited to examinations by radiologists and ultrasound technicians. Although contrast venography is considered the criterion standard for diagnosis of DVT, time, personnel, cost, exposure to radiation, and the invasive nature of the study (need for venous access) potentially limit the ability to perform the study in an emergent setting. Ultrasonography is an alternative method for thrombus detection and is widely preferred. However, in many health care settings, consultative ultrasound services may not be available immediately, especially after hours and on weekends. Based on recent studies demonstrating accuracy in adult patients, emergency sonographic evaluation of DVT by emergency physicians is considered a core emergency ultrasound application and is recently recommended as standard training to all emergency medicine residents. The diagnosis of DVT in children by emergency ultrasound in the pediatric ED has not been previously described. We present 3 cases of DVT in adolescents identified by emergency ultrasound evaluation in the pediatric ED.