Among all of the cathecolamines used for cardiac arrest treatment, epinephrine injection during cardio-pulmonary resuscitation is currently the most powerful means of enhancing effectiveness; however, deliberations about the optimal dosage have recently become intense. In the SAMU of Lyon (F), we conducted a double blind prospective randomized study over an 18-month period, comparing repeated standard-dose epinephrine (1 mg) and repeated high-dose epinephrine (5 mg) in the management of cardiac arrest outside the hospital. Five-hundred thirty-six patients were enrolled with 265 in the standard-dose group and 271 in the high-dose group; both groups are globally similar. One-hundred eighty-one (33.8%) patients returned to spontaneous circulation (R.O.S.C.); 85 in the standard-dose group (32%) and 96 in the high-dose group (35.5%). One-hundred nineteen patients (22.2%) were admitted; 54 in the standard-dose group (20.4%) and 65 in the high-dose group (24%). At 6 months nine patients (7.6%) were alive; three patients from the standard-dose group (5.5%) and six from the high-dose group (9.2%). We never noticed cardiac or neurologic adverse effects with the high doses. The results of this study are not statistically significant, but we observed a marginal trend towards repeated 5 mg epinephrine doses. A large French multicentre study is now necessary.