Aims Myocardial dysfunction is well described after out-of-hospital cardiac arrest (OHCA); however, the underlying mechanisms are not yet understood. We hypothesized that this dysfunction is associated to a global myocardial oedema. Using cardiac magnetic resonance (CMR), we assessed the presence of such oedema early after successful resuscitation from OHCA. Methods and results Comatose patients resuscitated from OHCA and admitted to the cardiac intensive care unit were consecutively included and underwent CMR in general anaesthesia within 36 h after cardiac arrest with anaesthetic support. To assess global myocardial oedema, T1 and T2 segmented maps were generated from three representative short-axis slices, and values from each segment were then used to determine a mean global T1 and T2 time for each patient. Healthy subjects were used as controls. CMR was obtained in 16 patients and compared with nine controls. The OHCA patients were 60 ± 9 years old, and acute myocardial infarction (MI) was diagnosed in six cases. On admission, left ventricular ejection fraction assessed by transthoracic echocardiography was 35 ± 15%, and this improved significantly to 43 ± 14% during hospitalization (P < 0.05). Mean global T1 and T2 time was significantly higher in OHCA patients compared with the control group (1071 ms vs. 999 ms, P = 0.002, and 52 ms vs. 46 ms, P < 0.001, respectively), and this difference remained significant when segments involved in the MI were excluded. Conclusion Assessed with CMR, we for the first time document an early global myocardial oedema in patients successfully resuscitated from OHCA.