External chest compressions (ECCs), which form the main part of Basic Life Support (BLS), must be carried out until Advanced Life Support can commence. It is essential to perform ECCs to the correct depth and frequency to guarantee effectiveness. Due to the absence of gravity, performing ECCs during a spacefl ight is more challenging. The three main BLS methods (Fig. 1) that can be used in microgravity are the Handstand (HS), the Reverse Bear Hug (RBH) and the Evetts-Russomano (ER), which have been studied separately in parabolic fl ights (2,3). The fi ndings suggested that the depth and frequency of the ECCs achieved during the microgravity parabolas were in accordance with the guidelines set by the American Heart Association (6) and the European Resuscitation Council (4), at the time of the studies. The wellknown main limitation of a parabolic fl ight is that it gives only 22 s of weightlessness, restricting a more complete evaluation of BLS methods. The ER method, however, has been extensively studied using a body suspension device as a ground-based microgravity simulator (5). This preliminary experiment aimed to compare the three main BLS models on the performance of the ECCs during ground-based microgravity simulation.