Background Acute coronary syndrome is a common cause of out-of-hospital cardiac arrest (OHCA). In patients with OHCA presenting with ST elevation, immediate coronary angiography and potential percutaneous coronary intervention (PCI) after return of spontaneous circulation are recommended. However, the evidence for this invasive strategy in patients without ST elevation is limited. Observational studies have shown a culprit coronary artery occlusion in about 30% of these patients, indicating the electrocardiogram's (ECG's) limited sensitivity. The aim of this study is to determine whether immediate coronary angiography and subsequent PCI will provide outcome benefits in OHCA patients without ST elevation. Methods/design We describe the design of the DIrect or Subacute Coronary angiography in Out-of-hospital cardiac arrest study (DISCO)—a pragmatic national, multicenter, randomized, clinical study. OHCA patients presenting with no ST elevation on their first recorded ECG will be randomized to a strategy of immediate coronary angiography or to standard of care with admission to intensive care and angiography after 3 days at the earliest unless the patient shows signs of acute ischemia or hemodynamic instability. Primary end point is 30-day survival. An estimated 1,006 patients give 80% power (α =.05) to detect a 20% improved 30-day survival rate from 45% to 54%. Secondary outcomes include good neurologic recovery at 30 days and 6 months, and cognitive function and cardiac function at 6 months. Conclusion This randomized clinical study will evaluate the effect of immediate coronary angiography after OHCA on 30-day survival in patients without ST elevation on their first recorded ECG.