Resuscitative thoracotomy (RT) is a time-sensitive, life-saving procedure performed by emergency physicians. The left anterolateral thoracotomy (LAT) is the standard technique commonly used in the United States to gain rapid access to critical intrathoracic structures. However, the smaller incision and subsequent limited exposure may not be optimal for the non-surgical specialist to complete time-sensitive interventions. The modified bilateral “clamshell” thoracotomy (MCT) developed by Bart’s Health clinician’s on London’s Air Ambulance (LAA), overcomes these inherent difficulties, maximizes thoracic cavity visualization and may be the ideal technique for non-surgical specialist. The aim of this study is to identify the optimal technique for the non-surgical specialist performed RT. Secondary aims of the study are to identify technical difficulties, procedural concerns and provider preferences. EM staff and senior resident physicians were recruited from a Level I trauma academic center. Subjects underwent newly developed standardized didactic and skills specific training on both the LAT and MCT techniques. At a later date, subjects were randomized to the order of intervention and performed both techniques on separate non-fixed, fresh human cadaver specimens. Success was determined by a board-certified surgeon and defined as complete delivery of the heart from the pericardial sac and subsequent 100% occlusion of the descending thoracic aorta with a vascular clamp. The primary outcome was the proportion of successful thoracotomies. Secondary outcomes included time to heart delivery, time to aortic cross-clamp, correct identification of critical anatomy, occurrence of iatrogenic injuries and provider preference. Sixteen emergency physicians were recruited; fifteen met inclusion criteria. All participants were either EM resident (47%) or EM staff (53%). The median number of previously performed training LATs was 12 (IQR 6-15) and the median number of previously performed MCTs was 1 (IQR 1-1, p<0.0001). The success rates for the LAT and MCT techniques were not statistically different (40% vs 67%, p=0.1573). The time to successful delivery of the heart, successful cross-clamp of the aorta and overall procedural success were not statistically different. There was a 63% absolute difference between Staff EM providers success with the MCT compared to LAT, but this did not meet statistical significance (88% vs 25%, p=0.0588). The MCT had a significantly higher proportion of injury-free trials compared to the LAT technique (33% vs 0%, p=0.0253). Provider procedure preference favored the MCT over the LAT (87% vs 13%, p=0.0045). The MCT and LAT technique success rates and procedural times were similar when performed by non-surgical specialists (emergency physicians). The MCT produced less iatrogenic injuries and was preferred by the majority of subjects. Staff emergency physicians were more successful with the MCT, although this did not meet statistical significance. The overall procedural success rate was lower than anticipated given the capable subject population and suggests further study is needed to identify gaps in procedural training, maintenance of competency, and performance. The MCT may be the ideal technique for the non-surgical specialist and should be further evaluated for routine use by emergency physicians.