BACKGROUND: In many countries emergency departments (EDs) are facing an increase in demand for services, long-waits and severe crowding. One response to mitigate overcrowding has been to provide primary care services alongside or within hospital EDs for patients with non-urgent problems. It is not known, however, how this impacts the quality of patient care, the utilisation of hospital resources, or if it is cost-effective. OBJECTIVES: To assess the effects of locating primary care professionals in the hospital ED to provide care for patients with non-urgent health problems, compared with care provided by regular Emergency Physicians (EPs), SEARCH METHODS: We searched the Cochrane Effective Practice and Organisation of Care (EPOC) Group Specialized register; Cochrane Central Register of Controlled Trials (The Cochrane library, 2011, Issue 4), MEDLINE (1950 to March 21 2012); EMBASE (1980 to April 28 2011); CINAHL (1980 to April 28 2011); PsychINFO (1967 to April 28 2011); Sociological Abstracts (1952 to April 28 2011); ASSIA (1987 to April 28 2011); SSSCI (1945 to April 28 2011); HMIC (1979 to April 28 2011), sources of unpublished literature, reference lists of included papers and relevant systematic reviews. We contacted experts in the field for any published or unpublished studies, and hand searched ED conference abstracts from the last three years. SELECTION CRITERIA: Randomised controlled trials, non-randomised studies, controlled before and after studies and interrupted time series studies that evaluated the effectiveness of introducing primary care professionals to hospital EDs to attend to non-urgent patients, as compared to the care provided by regular EPs. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data and assessed the risk of bias for each included study. We contacted authors of included studies to obtain additional data. Dichotomous outcomes are presented as risk ratios (RR) with 95% confidence intervals (CIs) and continuous outcomes are presented as mean differences (MD) with 95% CIs. Pooling was not possible due to heterogeneity. MAIN RESULTS: Three non randomised controlled studies involving a total of 11 203 patients, 16 General Practioners (GPs), and 52 EPs, were included. These studies evaluated the effects of introducing GPs to provide care to patients with non-urgent problems in the ED, as compared to EPs for outcomes such as resource use. The quality of evidence for all outcomes in this review was low, primarily due to the non-randomised design of included studies.The outcomes investigated were similar across studies; however there was high heterogeneity (I(2)>86%). Differences across studies included the triage system used, the level of expertise and experience of the medical practitioners and type of hospital (urban teaching, suburban community hospital).Two of the included studies report that GPs used significantly fewer healthcare resources than EPs, with fewer blood tests (RR 0.22; 95%CI: 0.14 to 0.33; N=4641; RR 0.35; 95%CI 0.29 to 0.42; N=4684), x-rays (RR 0.47; 95% CI 0.41 to 0.54; N=4641; RR 0.77 95% CI 0.72 to 0.83; N=4684), admissions to hospital (RR 0.33; 95% CI 0.19 to 0.58; N=4641; RR 0.45; 95% CI 0.36 to 0.56; N=4684) and referrals to specialists (RR 0.50; 95% CI 0.39 to 0.63; N=4641; RR 0.66; 95% CI 0.60 to 0.73; N=4684). One of the two studies reported no statistically significant difference in the number of prescriptions made by GPs compared with EPs, (RR 0.95 95% CI 0.88 to 1.03; N=4641), while the other showed that GPs prescribed significantly more medications than EPs (RR 1.45 95% CI 1.35 to 1.56; N=4684). The results from these two studies showed marginal cost savings from introducing GPs in hospital EDs.The third study (N=1878) failed to identify a significant difference in the number of blood tests ordered (RR 0.96; 95% CI 0.76 to 1.2), x-rays (RR 1.07; 95%CI 0.99 to 1.15), or admissions to hospital (RR 1.11; 95% CI 0.70 to 1.76), but reported a significantly greater number of referrals to specialists (RR 1.21; 95% CI 1.09 to 1.33) and prescriptions (RR 1.12; 95% CI 1.01 to 1.23) made by GPs as compared with EPs.No data were reported on patient wait-times, length of hospital stay, or patient outcomes, including adverse effects or mortality. AUTHORS' CONCLUSIONS: Overall, the evidence from the three included studies is weak, as results are disparate and neither safety nor patient outcomes have been examined. There is insufficient evidence upon which to draw conclusions for practice or policy regarding the effectiveness and safety of care provided to non-urgent patients by GPs versus EPs in the ED to mitigate problems of overcrowding, wait-times and patient flow.