BACKGROUND: Preliminary data suggested a clinical benefit in treating out-of-hospital cardiac arrest (OHCA) patients with a high dose of erythropoietin (Epo) analogs. OBJECTIVES: The authors aimed to evaluate the efficacy of epoetin alfa treatment on the outcome of OHCA patients in a phase 3 trial. METHODS: The authors performed a multicenter, single-blind, randomized controlled trial. Patients still comatose after a witnessed OHCA of presumed cardiac origin were eligible. In the intervention group, patients received 5 intravenous injections spaced 12 h apart during the first 48 h (40,000 units each, resulting in a maximal dose of 200,000 total units), started as soon as possible after resuscitation. In the control group, patients received standard care without Epo. The main endpoint was the proportion of patients in each group reaching level 1 on the Cerebral Performance Category (CPC) scale (survival with no or minor neurological sequelae) at day 60. Secondary endpoints included all-cause mortality rate, distribution of patients in CPC levels at different time points, and side effects. RESULTS: In total, 476 patients were included in the primary analysis. Baseline characteristics were similar in the 2 groups. At day 60, 32.4% of patients (76 of 234) in the intervention group reached a CPC 1 level, as compared with 32.1% of patients (78 of 242) in the control group (odds ratio: 1.01; 95% confidence interval: 0.68 to 1.48). The mortality rate and proportion of patients in each CPC level did not differ at any time points. Serious adverse events were more frequent in Epo-treated patients as compared with controls (22.6% vs. 14.9%; p = 0.03), particularly thrombotic complications (12.4% vs. 5.8%; p = 0.01). CONCLUSIONS: In patients resuscitated from an OHCA of presumed cardiac cause, early administration of erythropoietin plus standard therapy did not confer a benefit, and was associated with a higher complication rate. (High Dose of Erythropoietin Analogue After Cardiac Arrest [Epo-ACR-02]; NCT00999583).