Echocardiography is an essential tool in the evaluation of patients with cardiac emergencies and chest trauma. The objective of our study was to establish the feasibility and diagnostic accuracy of a portable satellite transmission system in the assessment of cardiac emergencies for the real-time support of mass casualty and humanitarian relief efforts. Twelve patients with various degrees of cardiac structural disease identified by conventional inhospital transthoracic echocardiography were transported to a remote portable field hospital where transthoracic echocardiography was performed with a handheld echocardiographic device. Images were then relayed by a commercial satellite to a level III trauma center where they were interpreted in real time by a cardiologist. Remote studies were recorded at the field hospital before satellite transmission and again on download at the receiving facility. The remotely acquired studies before and after satellite transmission were compared with each other and subsequently compared with conventional hospital transthoracic echocardiograms for technical quality and diagnostic accuracy using a blinded, single-reader, side-by-side comparison. Excellent agreement was found between the recorded field-site and satellite-transmitted images with an overall average of 95% concordance. When the field data acquired with the handheld device and satellite transmission were compared with conventional inhospital echocardiography, a high degree of agreement was demonstrated in overall technical quality (83%) and assessments of left ventricular ejection fraction (100%), pericardial effusion (100%), and left ventricular size (92%). This study demonstrates the feasibility and diagnostic accuracy of remote, real-time echocardiography using satellite transmission for mass casualty triage or humanitarian relief efforts.