Background It is estimated that about 275,000 inhabitants experience an out-of-hospital cardiac arrest (OHCA) every year in Europe. Survival in out-of-hospital cardiac arrest is relatively low, generally between five per cent and 10%. Being able to explore new methods to improve the relatively low survival rate is vital for people with these conditions. Passive leg raise (PLR) during cardiopulmonary resuscitation (CPR) has been found to improve cardiac preload and blood flow during chest compressions. The aim of our study is to evaluate whether early PLR during CPR also has an impact on one-month survival in sudden and unexpected out-of-hospital cardiac arrest (OHCA). Method/Design A prospective, randomized, controlled trial in which all patients (≥18 years) receiving out-of hospital CPR are randomized by envelope to be treated with either PLR or in the flat position. The ambulance crew use a special folding stool which allows the legs to be elevated about 20 degrees. Primary end-point: survival to one month. Secondary end-point: survival to hospital admission to one month and to one year with acceptable cerebral performance classification (CPC) 1–2. Discussion PLR is a simple and fast maneuver. We believe that the greatest benefit with PLR is when performed early in the process, during the first minutes of CPR and before the first defibrillation. To reach power this study need 3000 patients, we hope that this method article will encourage other sites to contact us and take part in our study. Trial registration ClinicalTrials.gov NCT01952197.