Objectives. Triage processes are often used by Emergency Departments to sort patients according to urgency or type of service required. Triage may also be used in a broad spectrum of other health services and not just emergency departments. Triage systems may be used to ensure the most urgent patients get timely service, but do they have an effect on patient flow? Methods. We conducted a systematic review by searching five electronic databases (until August 2009) combining the elements ‘triage’ and ‘patient flow’, complemented by hand searching reference lists and citation tracking. We identified and assessed the quality of 25 articles that met inclusion criteria. Population, setting, design and results were extracted and a process of descriptive synthesis applied. Effect sizes for waiting time were compared for seven studies in which sufficient data could be extracted. Results and conclusion. Moderate evidence exists from a range of health services that the ability to combine triage and initial treatment in less resource intensive cases can have a positive effect on patient flow. There is conflicting evidence that triage systems that only prioritise patients, without providing any treatment, improve overall patient flow, although tailoring triage criteria more specifically to the patient population or using triage to prioritise treatable cases may be of benefit. What is known about the topic? Triage systems are widely used across many health services. Triage systems that combine treatment and triage have been found to improve patient flow in emergency departments, but the effect of more basic triage systems on patient flow and the effect of triage on patient flow in other settings has not been widely examined. What does this paper add? The results of this review reinforce previous findings from emergency departments, but also suggests that these principles can be used to enhance triages systems and improve patient flow in other healthcare settings. What are the implications for practitioners? Triage systems can improve patient flow, and providing some options for management of simple cases at the point of triage is likely to be of benefit in achieving this outcome across a broad spectrum of health services.