Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. Interventions aiming at reducing prehospital delay (PHD) in patients with acute coronary syndrome (ACS) have yielded inconsistent findings. Therefore, we aimed to systematically review studies which investigated the impact of educational interventions on reducing PHD in patients with ACS. We searched four electronic databases (Cumulative Index to Nursing and Allied Health Literature, MEDLINE, Embase, Cochrane) from inception throughout December 2016 for studies that reported the impact of either mass-media or personalised intervention on PHD. Reporting quality was assessed with the Template for Intervention Description and Replication checklist for interventional trials. Two reviewers screened 12 184 abstracts and performed full-text screening on 86 articles, leading to 34 articles which met our inclusion criteria. We found 18 educational interventions with a total of 180 914 participants (range: n=100-125 161) and a median of 1342 participants. Among these educational interventions, 13 campaigns employed a mass-media approach and five a personalised approach. Ten studies yielded no significant effects on the primary outcome while the remaining interventions reported a significant reduction with a decrease between 17 and 324 min (median reduction: 40 min, n=5). The success was partly driven by an increase in emergency medical services use. Two studies reported an increase in acute myocardial infarction knowledge. We observed no superiority of the personalised over the mass-media approach. Although methodological shortcomings and the heterogeneity of included interventions still do not allow definite recommendations for future campaigns, it becomes evident that either mass media or personalised interventions can be successful in reducing PHD, especially those who address behavioural consequences and psychological barriers (eg, denial) and provide practical action plan considerations as part of their campaign messages. CRD42017055684 (PROSPERO registration number).