ObjectiveGuideline and protocol adherence in prehospital and in-hospital emergency departments (EDs) is suboptimal. Therefore, the objective of this systematic review was to identify effective strategies for improving guideline and protocol adherence in prehospital and ED settings.DesignSystematic review.Data sourcesPubMed (including MEDLINE), CINAHL, EMBASE and Cochrane.MethodsWe selected (quasi) experimental studies published between 2004 and 2018 that used strategies to increase guideline and protocol adherence in prehospital and in-hospital emergency care. Pairs of two independent reviewers performed the selection process, quality assessment and data extraction.ResultsEleven studies were included, nine of which were performed in the ED setting and two studies were performed in a combined prehospital and ED setting. For the ED setting, the studies indicated that educational strategies as sole intervention, and educational strategies in combination with audit and feedback, are probably effective in improving guideline adherence. Sole use of reminders in the ED setting also showed positive effects. The two studies in the combined prehospital and ED setting showed similar results for the sole use of educational interventions.ConclusionsOur review does not allow firm conclusion on how to promote guideline and protocol adherence in prehospital emergency care, or the combination of prehospital and ED care. For ED settings, the sole use of reminders or educational interventions and the use of multifaceted strategies of education combined with audit and feedback are all likely to be effective in improving guideline adherence.