BACKGROUND:Many people wait long periods for community outpatient services. However little is known about the impact of waiting from referral to first visit on patient outcomes. The aim of this systematic review is to investigate whether waiting for community outpatient services is associated with adverse effects on patient outcomes. METHODS:Medline, Embase, Psych Info and CINAHL databases were searched, combining the key concepts of waiting for healthcare and patient outcomes. Studies were included if they reported data comparing health outcomes for patients with different waiting times for the same period. Three reviewers applied inclusion and exclusion criteria to identified studies and assessed quality using the McMaster Critical Review Forms. Levels of evidence were assessed using National Health and Medical Research Council guidelines. Included studies were analysed using a descriptive synthesis, and summarised according to levels of evidence and clinical significance for key outcomes. RESULTS:Fourteen studies that included 69,606 adult patients were selected. Selected studies included patients referred for treatment for musculoskeletal disorders (n = 28,722) or to cardiac rehabilitation (n = 40,884). There was low-level evidence that reduced wait time is associated with moderate improvement in workplace participation for patients seeking care for musculoskeletal conditions; and moderate improvement in exercise tolerance for patients referred to cardiac rehabilitation. There was inconsistent evidence that improvements in quality of life, patient satisfaction and psychological symptoms may be associated with shorter wait times. Pain, function and physical activity outcomes were not associated with wait time. CONCLUSIONS:This review found low-level evidence suggesting an association between early access to community outpatient services and improvement of some patient outcomes. Specifically, shorter wait times from referral to first visit for musculoskeletal pain services may improve patient work participation. Shorter wait times for cardiac rehabilitation may improve patient exercise capacity. The effects of a short wait time for other patient conditions and patient outcomes, including quality of life, psychological symptoms and patient experience, are inconclusive. The modest benefits in health outcomes observed in reducing wait time for community outpatient services suggest that other possible benefits such as increasing patient flow should be explored. TRIAL REGISTRATION:PROSPERO registration no: CRD42016047003.